Number bonds for 10 song. Number bonds are simply the pairs of numbers that make up a given number. Number bonds can also be called number partners or number pairs. Number bonds are a very important foundation for understanding how numbers work. Number bonds create fluency for composing and decomposing numbers for addition and subtraction. By the end of Year 1, every child should know their number bonds to 10 and 20. This video is a fun way to learn them all.