Everyday Math

Multiples of 5 include: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, ... Common method of multiplying numbers by 5:  Another technique in dealing with multiplication by 5 (which I often use to make it easier for me to solve this mentally) is: Choose for yourself which is easier then try doing it mentally. In dealing with odd numbers, I usually convert it to an even number first by multiplying it with 10 before dividing it by 2.

Try to make it second nature to you to mentally find products for common factors such as 4 and 3, 7 and 6, 9 and 10, and others. This would greatly aid you in solving multiplication problems involving larger numbers. You can see several wonderful patterns in this table. 1 obviously retains the value of the number being multiplied to it Any number multiplied to 2 gives an even number as its product When you add the digits of products with 3 as one of their factors, the sum would be divisible by 3. Divisible, meaning you can divide the said sum by 3 and not get any remainder from the division process Any number multiplied to 4 also gives an even number as its product Any number multiplied to 5 gives a product with its ones digit ending in 0 if it is multiplied to an even number, or 5 if multiplied to an odd number The multiples of 6 are even numbers and the sum of their digits are divisible by 3 Numbers multiplied to 10 will always have products ending in zero. Numbers in r...