《MathStart》系列為美國HarperCollins出版的暢銷數學啟蒙書。作者Stuart J. Murphy認為數學與日常生活息息相關，他為了建立小朋友基礎的數學概念與知識，讓小朋友輕鬆愉快地學習數學，因而精心設計了這套生活化的《MathStart》數學啟蒙繪本，從生活話題與情境故事，讓小朋友有效地吸收數學概念。
全系列分為三個Level，Level 1著重於基礎認知上。
《Monster Musical Chair》主要用怪獸在玩音樂椅，帶出每次一隻怪獸出局的減數概念。
書內還會介紹不同的遊戲讓小朋友強化《減數》的概念。
同系列書藉：
Math Start Level 1 Double the Ducks
When six monsters get together to play musical chairs, you'd better watch out! "Stomp, stomp, SNORT. Shake, shimmy, SHOUT! When the music stops, one monster is OUT!," sings the leader of the monster band. One by one the players are tagged out until there's only one left: The winner!
Knowing how many objects are left when one is taken away from a group is a first step in understanding the concept of subtraction.
Books in the same series:
Math Start Level 1 Double the Ducks
Paperback / For Ages: 3-7 / 40 pages