Give the expression
a) 2.34+3.89
First thing you can do is to write as a whole number and as a decimal
2.34 = 2+0.34
3.89 = 3+0.89
2.34+3.89 = 2+0.34+3+0.89
collect the like terms
2.34+3.89 = 2+3+0.34+0.89
2.34+3.89 = 5+1.23
2.34+3.89 = 6.23
b) 3.77+2.22
3.77 = 3+0.77
2.22 = 2+0.22
3.77+2.22 = 3+0.77+2+0.22
3.77+2.22 = 3+2+0.77+0.22
3.77+2.22 = 5+0.99
3.77+2.22 = 5.99