↑ Return to Number Sense Video Lessons
↑ Return to Number Sense Video Lessons
47 comments
Skip to comment form ↓
Bryan Neal
November 9, 2014 at 11:35 pm (UTC 0) Link to this comment
Hi there. Thanks for the number sense video resources/tricks. Using different platforms for students to learn this year has been a new thing I have been searching for. Thanks so much.
Bryan Neal
S.C.
April 9, 2015 at 12:30 am (UTC 0) Link to this comment
Thank you for these awesome tricks. You are very thoughtful for posting these videos on top of being a teacher and teaching your own students. My score has increased magnificently. Thank you so much!
anthony gillespey
April 28, 2015 at 7:59 pm (UTC 0) Link to this comment
Your welcome, I’m going to start working on a Calculator book and video series sometime this summer.
Lightning
May 29, 2015 at 10:02 pm (UTC 0) Link to this comment
Hello. I was wonder if there was a trick for multiplying 43×34 or 67×76. Like a reflection trick. Thank you.
anthony gillespey
June 8, 2015 at 4:58 pm (UTC 0) Link to this comment
I don’t know of one although Ill spend sometime on the Algebra and see if i can find something.
Math Rocks
April 26, 2016 at 11:50 pm (UTC 0) Link to this comment
u can use foil
anthony gillespey
June 9, 2015 at 7:32 pm (UTC 0) Link to this comment
Just changed the formatting for the pages with videos. Each video now has its own page. I had a problem with the plugin I used for the page and had to change it a bit. Let me know if anyone sees mistakes.
Adhav
October 10, 2015 at 1:52 am (UTC 0) Link to this comment
Is there a shortcut to this problem?
If there is can you help me solve this problem.
9 2/15 – 5 4/5 = ?
Thank you
anthony gillespey
October 20, 2015 at 9:48 pm (UTC 0) Link to this comment
Not really for this one. Just crunch the numbers like normal.
Math Rocks
April 26, 2016 at 11:50 pm (UTC 0) Link to this comment
What I did when I saw that question on the MSNS was I did 4/5 and made that 12/15. Then, I subtracted 12/15 from 2/15. I did this by going up from 12 to 15 (add 3) and then I added 2 to get 1 and 2/15. I added 5/15 to 12/15 to get to (1 and) 2/15. 5/15 simplified is 1/3. Then, since I went UP 5/15 to solve for the fraction, I did 9-5, which is 4, but since I went UP to simplify the fraction, I subtracted 1 more time, to get 3 and 1/3 as my answer. This probably won’t even make sense to you, but if it does, I hope it works later in the future. It’s easier to explain it visually.
Adhav
June 11, 2016 at 3:08 pm (UTC 0) Link to this comment
Thanks
anthony gillespey
April 27, 2016 at 1:11 am (UTC 0) Link to this comment
Another interesting way is to be OK with negative answers. 9-5=4 and 2/15 – 4/5 = 2/15 -12/15 = – 10/15 so you get 4 and – 2/3 or 3 and 1/3. Which is nice since the numbers stayed small.
Adhav
June 11, 2016 at 3:09 pm (UTC 0) Link to this comment
Thanks
Jake
October 22, 2015 at 1:36 am (UTC 0) Link to this comment
Is there an easy way to multiply a 3 digit number by another 3 digit number
Ex:
565*344
anthony gillespey
October 26, 2015 at 1:18 pm (UTC 0) Link to this comment
Are you doing Number Sense Tests? If so I think you are doing an estimation question. If that is the case you dont really care what the exact answer is. If I was doing this question you asked with estimation then is alot easier. 565*344 is really close to 560 * 333. which would be 560 *1/3 with some zeroes. Which is really easy.
Mia hinojosa
November 9, 2015 at 2:09 am (UTC 0) Link to this comment
Hey do you know the 33 1/3 trick I could not find it in your book?
anthony gillespey
November 13, 2015 at 7:10 pm (UTC 0) Link to this comment
33 and 1/3 is basically 1/3 think of it as 1/3 and do the math then figure out how many zeroes to add.
Math Rocks
January 6, 2016 at 1:20 am (UTC 0) Link to this comment
Hello. On the Cross Timbers Number Sense Test on October 2015, there was a question (question 76) that I didn’t know any trick for. It wasn’t an estimation question either, so I was wondering how to do it. The question was, 143 x 133. Can you tell me how to solve this if there is a way to? Thanks.
anthony gillespey
January 16, 2016 at 3:55 am (UTC 0) Link to this comment
I’ll give you a hint 143 is a multiple of 7.
Math Rocks
January 23, 2016 at 3:15 am (UTC 0) Link to this comment
Thanks. I saw it on page 28
Adhav
January 11, 2016 at 1:16 am (UTC 0) Link to this comment
is there a trick for multiplying 213 by 138?
Math Rocks
March 1, 2016 at 12:11 am (UTC 0) Link to this comment
I don’t know if this will help, but I found that 213 = 71 x 3, and 138 = 23 x 6, or 23 x 2 x 3.
anthony gillespey
March 2, 2016 at 2:02 pm (UTC 0) Link to this comment
I discovered those myself not to long ago. I think in later editions of the book I will include those. Thanks.
Math Rocks
February 19, 2017 at 8:46 pm (UTC 0) Link to this comment
you should round 138 to 140 and 213 to 200
Math Rocks
April 20, 2016 at 1:17 am (UTC 0) Link to this comment
Well, Flour Bluff has dominated once again. I’m from Fowler, and we got 3rd place. I can’t understand how Flour Bluff could get 5100 points! They’re so good, but next year our school will probably be moved down to 4A because there is a new school coming in. But anyways, I’ll get to the point. Mr. Gillespy, I have a question for you about the recent state test. How do you number 53, which states A set with 10 elements has how many 7-element subsets? BTW, I got 5th place in Number Sense!
anthony gillespey
April 20, 2016 at 1:29 pm (UTC 0) Link to this comment
Fowler did really good this year. You guys gave us a run for our money and should be extremely proud of your results. Having you guys in 5A definitely makes the contest more exciting.
Great job getting 5th at state I know that was incredibly hard to do. hopefully my book helped.
To answer your question about question 53, subsets with certain amounts are just variations of Combinations so just think of it as a 10 choose 7 combination which is 10!/ (7! x 3!)
Math Rocks
April 25, 2016 at 3:54 am (UTC 0) Link to this comment
Thanks Mr. Gillespy. Your book helped a lot too. I just have one more question. How do you solve this: The slope of a line with x-intercept of (5, 0) and a y-intercept of (0, –2) is?
anthony gillespey
April 27, 2016 at 1:04 am (UTC 0) Link to this comment
What are you asking.? The slope or the equation of the line?
Math Rocks
May 30, 2016 at 5:34 pm (UTC 0) Link to this comment
slope
Math Rocks
January 29, 2017 at 5:50 pm (UTC 0) Link to this comment
never mind… I made a simple mistake while trying to do y1-y2/x1-x2
Math Rocks
April 26, 2016 at 11:41 pm (UTC 0) Link to this comment
We might not be in 5A next year, because there is a new high school coming in next year, and it will probably lower the population which might place us in 4A. Can you answer the question I asked you?
Thx
Lightning
December 20, 2016 at 6:18 pm (UTC 0) Link to this comment
Can u please make a calculator section tricks to ur website. I have a bit of trouble with it.
anthony gillespey
January 12, 2017 at 8:10 pm (UTC 0) Link to this comment
Someday I will get around to it. Not ready to do that just yet.
Math Rocks
February 15, 2017 at 3:11 am (UTC 0) Link to this comment
Hi Mr. Gillespy,
How do you do a problem like a times b/c. An example is 16 x 19/21. I know you can do it in your head but I was wondering if there was a fast way
Math Rocks
February 15, 2017 at 3:13 am (UTC 0) Link to this comment
Hi Mr. Gillespy,
How do you do a problem like a times b/c. An example is 16 x 19/21. I know you can do it in your head but I was wondering if there was a fast way
Math Rocks
February 18, 2017 at 12:02 am (UTC 0) Link to this comment
sorry for commenting the same comment two times, my computer was facing some problems and I think I double clicked the send button for the comment
anthony gillespey
March 21, 2017 at 10:03 pm (UTC 0) Link to this comment
This problem is actually pretty hard to explain but ill give it a try. the key is that the denominator is 21. Subtract 19 and 16 from 21. You get 2 and 5. Multiply those numbers.
That is your new numerator. Your whole number is like the old trick. Since 19/21 is less than 1 you subtract the difference from 16. So the final answer is 14 10/21 . This gets harder when you multiply the numbers and they are negative. Look for this trick in my new book.
Jacob
November 9, 2017 at 12:54 pm (UTC 0) Link to this comment
Thanks so much for making this book. Our school Vandeventer benefits from it a lot!
anthony gillespey
November 13, 2017 at 7:39 pm (UTC 0) Link to this comment
Great to hear. Have a great season.
NK
February 8, 2018 at 11:15 pm (UTC 0) Link to this comment
does any of this help if you are taking the PSAT 8/9?
anthony gillespey
February 15, 2018 at 10:34 pm (UTC 0) Link to this comment
Some of it. General Math and Calculator would help more.
NK
September 9, 2018 at 2:20 pm (UTC 0) Link to this comment
This will help for math and science team, right?
MP
September 29, 2018 at 3:29 pm (UTC 0) Link to this comment
I was wondering if there was a trick for things like 1+2+3…+15=.
anthony gillespey
October 3, 2018 at 12:16 pm (UTC 0) Link to this comment
yep its in the book and videos.
FORTNITE
November 19, 2018 at 9:16 pm (UTC 0) Link to this comment
So, the double/double division trick is basically that since you have doubled both numbers when you divide it it comes out to the same number as the original equation, right?
anthony gillespey
December 31, 2018 at 9:19 pm (UTC 0) Link to this comment
yep
Smiley
January 29, 2019 at 1:39 am (UTC 0) Link to this comment
This is really helpful math and science learned alot