# How do you teach multiplication by 100?

**How to multiply and divide by 0, 1, 10 and 100**

- When you
**multiply**by 1 the answer stays the same. 21 × 1 = 21. - When you
**multiply**by 10, move all the digits one place to the left, putting a zero in the empty space. 21 × 10 = 210. - When you
**multiply by 100**, move all the digits two places to the left, putting a zero in the empty spaces. 21 ×**100**= 2100.

Regarding this, what is the rule for multiplying by 100?

**To multiply** any number by **100**, just tag TWO zeros on the end. **To multiply** any number by 1,000, just tag THREE zeros on the end. Note especially what happens when the number you **multiply** already ends in a zero or zeros. The **rule** works the same; you still have to tag the zero or zeros.

**1**(one, also called unit, and unity) is a

**number**, and a numerical digit used to represent that

**number**in numerals. It represents a single entity, the unit of counting or measurement. For example, a line segment of unit length is a line segment of length

**1**.

**1**is the smallest positive integer.

Keeping this in consideration, what are the multiplication strategies?

To multiply any number by 8, double the number. Then double the product and finally, double that product. To multiply any number by 9, multiply it by 10 and then subtract one set of that number. To multiply any number by 10, think of the number that is equal to that many tens.

A googol is a 1 with a hundred zeroes behind it. We can write a googol using exponents by saying a googol is 10^**100**. The biggest named number that we know is googolplex, ten to the googol power, or (10)^(10^**100**). That's written as a one followed by googol zeroes.