# 4th Grade Math Review: Day 5

In __yesterday's post__ we looked at adding and subtracting fractions and decimals. Today we are diving into multiplication, both 2-digit by 2-digit and multiplying be multiples of 10 or 100.

**Multiplying by 10 or 100**

One of the key mathematical elements that students need to understand is how to quickly multiply by 10 or 100 by simply adding zeros. Watch this video for an explanation.

With that under your belt, try to solve this problem from a released STAAR test.

**2-Digit Multiplication**

Now for the moment some students have been dreading for years - two by two multiplication! Watch the video below for some examples and to figure out why the second row always starts with zero.

With that information, now you can solve this problem.

Though the skill isn't always tested, 4th graders also need to know how to __multiply a 4-digit number by a 1-digit number__.

**Correct Answers
**Here's the video with the answers and explanations. Make sure you've worked them out yourself before watching.