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