## Pre-Algebra Tutorial

*Multiplying multiples of 10*

#### Intro

A simple trick to multiplying numbers ending in strings of zeroes (multiples of 10)

#### Sample Problem

Evaluate 250 * 40.

Evaluate 32 * 4000

#### Solution

The zeroes can be ignored until the end of the calculation.

Simply evaluate the product of the operands without the zeroes at the end,

and concatenate them to the answer.

25**0** * 4**0** => 25 * 4 = 100 => adding back the two zeroes becomes 100**00**

32 * 4**000** => 32 * 4 = 128 => adding back the 3 zeroes becomes 128**000**

Note that this trick applies to zeroes at the **END** of a number. Zeroes that occur inside the the number, e.g 4**0**2000 cannot be ignored

# About The Author

University Student Tutor For Elementary And Highsc |

My name is Robert Dee, and I am currently a student at Simon Fraser University. I excelled in mathematics throughout elementary and high school, frequently doing higher level mathematics than my classmates. I have also participated in multiple mathematics competitions (pascal, fermat etc..). I hav... |

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