World Book 
Subtraction 

Meet Subtraction they help us find the difference between two amounts! Subtraction is here to explain this core concept of mathematics to students through colorful and engaging examples. Readers will be introduced to counting back, number lines, and checking their work. Activities at the back of the book encourage readers to test their knowledge. Along the way students will meet famous mathematician Ada Lovelace, who wrote the first published computer program. A colorful timeline also introduces readers to the history of math. For more information on math strategies, check out other titles in the Building Blocks of Math series!