23-13=10 Twenty-three take away thirteen is ten. 28-20=8 Twenty-eight take away twenty is eight. 25-11=14 Twenty-five take away eleven is fourteen. 29-9=20 Twenty-nine take away nine is twenty. 27-13=14 Twenty-seven take away thirteen is fourteen. 24-15=9 Twenty-four take away fifteen is nine. 22-12=10 Twenty-two take away twelve is ten. 21-10=11 Twenty-one take away ten is eleven. 26-23=3 Twenty-six take away twenty-three is three.
28-20=8 Twenty-eight take away twenty is eight.
25-11=14 Twenty-five take away eleven is fourteen.
29-9=20 Twenty-nine take away nine is twenty.
27-13=14 Twenty-seven take away thirteen is fourteen.
24-15=9 Twenty-four take away fifteen is nine.
22-12=10 Twenty-two take away twelve is ten.
21-10=11 Twenty-one take away ten is eleven.
26-23=3 Twenty-six take away twenty-three is three.