February / March 2015 Newsflash: Tips & Techniques

By | Added Feb 12, 2015

 

Many times, mental math is a better way to solve math problems than using an algorithm. Here are two approaches to division using mental math.

 

Example 1: 75 ÷ 6

6 is the same as 2 x 3, so instead of dividing by 6, we can divide 75 by 3 and then divide that quotient by 2. So, 75 ÷ 3 = 25, and 25 ÷ 2 = 12 1/2. Done!!!

 

Try these:

 

1) 99 ÷ 6 = ____________

2) 75 ÷ 15 = _____________

3) 150 ÷ 12 = ______________

4) 430 — 20 = _______________

 

Example 2: 200 ÷ 25

 

Another way to look at division is to ask yourself, “How many of these are inside of that?” For 200 ÷ 25, ask yourself how many 25s are there inside 100. There are 4 25s in 100, so inside of 200 there must be twice as many; 8. So, 200 ÷ 25 = 8.

 

Try these:

 

1) 300 ÷ 25 = _____________

2) 90 ÷ 15 = _____________

3) 1,000 ÷ 125 = ______________

4) 6 — 1 1/2 = ______________