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Why Mental Math?
Mental math allows the
student to focus on the logic
of the problem instead of
the numbers.
It enables quick estimation
of magnitudes and develops
number sense.
“Alice drove at 25 miles per hour for 10 hours, and
Bob flew at 400 miles per hour for 3 hours. Who
traveled a greater distance? How far did they travel
altogether?”
A student skilled at mental math would quickly
answer: Alice traveled 250 miles, but Bob traveled
more than 400 miles so Bob traveled a greater
distance. Bob traveled 1200 miles, so together they
traveled 1,450 miles. A student unskilled at mental
math would be distracted by the large numbers,
would have to go back and re-read to find the
relationships between the numbers, and then
perform column multiplication in order to figure out
who traveled farther and column addition to finally
answer how far much they traveled altogether.
It boosts performance on
standardized tests: students
can breeze through easy
calculations and use their time
to focus on harder problems.
It is useful in everyday life
and in science and engineering
professions.
Calculating a 10% tip is a breeze, just move
the decimal point once to the left! And a 20% tip
is just twice that!
It helps students do column
multiplication and long division
quickly and accurately.
When using column multiplication to multiply
329 by 748, the student must perform single digit
multiplication and addition many times, as well as keep
track of the carry over. Mental math skills improve
both speed and accuracy.
It makes convenient calculation
possible.
It’s no use knowing that 17+ 28 + 13 = 17 + 13 + 28
if you can’t add 17 + 13!
It gives students confidence
in their mathematical
abilities.
“It’s so easy, I can even do it in my head!”
Every student can master it – all it takes is practice!
Mental math skill progression in RM Basic I:
Add/subtract within 10; Composition of numbers 2 – 10
Composition of numbers 11 – 20
Add/subtract without crossing over 10 in a number up to 20: 12 + 4 = 16, 16 – 3 = 13
Add/subtract with crossing over 10 in a number up to 20: 9 + 4 = 13, 16 – 7 = 9
Add/subtract within a single place value in a number up to 100: 20 + 3 = 23, 23 – 3 = 20, 23 – 20 = 3
Add/subtract round numbers up to 100: 30 + 50, 70 – 40
Add/subtract one-digit numbers without crossing over 10: 24 – 3 =21, 34 + 5 = 39
Add/subtract a two-digit number and a round number : 34 + 20 = 54, 54 – 40 = 14
Addition where the sum is a round number: 37 + 3 = 40
Subtraction of a one-digit number from a round number: 50 – 4 = 46
Add/subtract a two-digit number and a one-digit number with regrouping: 23 + 9 = 32, 76 – 8 = 68
Multiplication table
Multiplication and division (of round numbers) by 10: 27 x 10 = 270, 80 ÷ 10 = 8
Multiplication of a round number by a single-digit number: 20 x 4 = 80
Simple multiplication of a two-digit number and a one-digit number: 23 x 3 = 69
Simple division with a remainder: 9 ÷ 2 = 4 R1, 20 ÷ 3 = 6 R2
Multiplication and division (of round numbers) by 100: 7 x 100 = 700, 800 ÷ 100 = 8
Simple division of a two-digit number by a one-digit number: 36 ÷ 3 = 12