Mental Math

Beginning last year, more of a school wide emphasis was placed on students learning Mental Math Strategies.  These are “tricks”  that help students get the correct answer more easily!  Students learn these principles first through hands on activities and working with meaningful materials before being expected to know them automatically. Some of the strategies include:

1.      Making 10 (100, 1000, etc)

-         Students need to know all combinations quickly and automatically

-         75 + 30 + 25 =  put the 100 together then just add 30

2.      Adding 10, 100, 1000

-         10 +3 = 13 (the 1 means 1 ten)

-         100 +60 =  160!  (just put together!)

3.      Doubles

-         Students need to know how to add doubles quickly

(ex.  7+7, 70+70,  700 +700 etc)

4.      Compensation

-         Students look for ways to add on or take off an amount so that whatever is left is “easy” to work with (ie a 10’s number or a combination they know from above)

-         Doubles plus or minus 1

-         9 + 3 = (10 +3) – 1= 12

-         99- 50 it is easier to do 100 – 50 then subtract the extra 1

5.      Order Strategy

-         Changing the order of the numbers when adding or multiplying does not change the answer

6.      Multiplying by 10 or 100

-         same number of  zeros!

7.      Front End Addition / Subtraction

-         Add the hundred, then the tens and then the ones

-         Ex.  346 + 123 =