The number bonds to 20 are: 0 + 20 = 20

A number bond is just a maths fact that a pair of numbers when added together make a given total. For example the number bonds for 10 are 0+10=10, 1+9=10; 2+8=10, 3+7=10, 4+6=10, 5+5=10 etc, and the number bonds for 20 are 0+20 = 20, 1+19 = 20, 2+18 = 20 etc.