What are some of the easier ways to get at the following mentally:
a) 129 * 113
b) 131 * 143
c) 539 * 15 ( easier than add half of 5390 to 5390)
All of the above are from past TMSCA Elementary Number Sense Tests for Grades 4 & 5.
Thanks much,
Phil
forum.virtualchallengemeets.com
Your connection to the competitive math/science community. (Formerly texasmath.org)
Help with some number sense problems
6 posts
• Page 1 of 1
Help with some number sense problems
by texaslonghorn » Wed May 08, 2013 11:20 pm
- texaslonghorn
- Typical User
- Posts: 14
- Joined: Fri Jan 25, 2013 2:28 am
Re: Help with some number sense problems
by 101dalmatians » Thu May 09, 2013 7:12 am
I guess this signature really doesn't matter now that I know that the forum is going down soon...
-
101dalmatians - Ubiquitous Spammer
- Posts: 1013
- Joined: Mon Aug 27, 2012 6:30 pm
- Location: Dallas, Tx.
Re: Help with some number sense problems
by rcoker7 » Thu May 09, 2013 7:31 am
For c, I'd do 540 * 15 - 15 and do the normal 15 trick with 540.
Region scores
NS: 368
CALC: 308
MATH: 318
SCIENCE: 232(32,96,104)
NS: 368
CALC: 308
MATH: 318
SCIENCE: 232(32,96,104)
- rcoker7
- Determined Spammer
- Posts: 125
- Joined: Mon Mar 19, 2012 6:05 pm
Re: Help with some number sense problems
by texaslonghorn » Fri May 10, 2013 10:34 pm
Thanks much for the help!
- texaslonghorn
- Typical User
- Posts: 14
- Joined: Fri Jan 25, 2013 2:28 am
Re: Help with some number sense problems
by texaslonghorn » Sun May 12, 2013 3:58 pm
To answer 111*452, would Triple LOIF be the best method or are there better alternatives?
Thanks,
Phil
Thanks,
Phil
- texaslonghorn
- Typical User
- Posts: 14
- Joined: Fri Jan 25, 2013 2:28 am
Re: Help with some number sense problems
by Fredfredburger » Sun May 12, 2013 7:26 pm
You can also extend that to multiplying by 1111 and 11111.
MIT '17
-
Fredfredburger - Determined Spammer
- Posts: 115
- Joined: Sat Mar 31, 2012 9:33 am
- Location: El Paso
6 posts
• Page 1 of 1
Who is online
Users browsing this forum: No registered users and 4 guests