Archios: Multiplication Rules in 3rd and 4th Grade

By 2, if the unit digit is even.

By 3, if the sum of its digits is divisible by 3.

By 4, if the last tow digits are divisible by 4.

By 5, if the unit digit is 0 or 5.

By 6, if it is divisible by both 2 and 3

By 8, if the last three digits are divisible by 8

By 9, if the sum of the digits is divisible by 9.

By 12, if divisible by both 3 and 4

To multiply by

5, add zero and divide by 2.

15, add 2 zeros and divide by 4.

125, add 3 zeros and divide by 8.

15, multiply by 30 and divide by 2.

35, multiply by 70 and divide by 2.

75, multiply by 300 and divide by 4.

12 ½, add 2 zeros and divide by 8.

DIVISION

To divide by:-

5, multiply by 2 and divide by 10.

25, multiply by 2 and divide by 100.

125, multiply by 8 and divide by 1,000

75, multiply by 4 and divide by 300.

375, multiply by 8 and divide by 3,000