Mentally Adding Two-Digit Numbers How to mentally add two two-digit numbers. Add 84 and 35. First add the two ones' place digits (4 + 5 = 9). Next add the two tens' place digits (8 + 3 = 11). The sum of the ones' place digits is less than ten so the answer is 119   Add 94 and 67. First add the two ones' place digits (4 + 7 = 11). Next add the two tens' place digits (9 + 6 = 15). The sum of the ones' place digits is a two-digit number so decrease the ones' place sum by 10 (11 - 10 = 1) increase the tens' place sum by 1 (15 + 1 = 16) Combine the tens' and ones' place sums to give the answer of 161 Another method to mentally add two two-digit numbers may be easier in some situations. Add 84 and 35. First add the two tens' place digits (8 + 3 = 11). Next add the two ones' place digits (4 + 5 = 9). The sum of the ones' place digits is less than ten so the answer is 119.   Add 94 and 67. First add the two tens' place digits (9 + 6 = 15). Next add the two ones' place digits (4 + 7 = 11). The sum of the ones' place digits is more than nine so: Decrease the ones' place sum by 10 (11 - 10 = 1.) Increase the tens' place sum by 1 (15 + 1 = 16). Combine the tens' and ones' place sums to give the answer of 161 Return to Top

#### Find the Sum of the two Numbers.

 +     =