2-digit number +1-digit number Putuo District Changzheng Central Primary School, Shanghai Coco朱文静

Warm up! 23 + 20= 43 20＋20＝40 tens ones 40＋3＝43

Task1 43 ？ 23 + 2 =

23 + 2 = 25 tens ones

Practice I 23 + 4 = 27 tens ones 3＋ 4＝7 20＋ 7＝27

Practice II 23 + 6 = 29 3 + 6 = 9 20 + 9 = 29

Task ２　Notice !　　 23 + 6 = 3 6 29 9 23 + 2 = 25 3 2 5 23 + 4 = 27 3 4 7

Just add in the 23’s ones place Task ２　Notice !　　 2 4 6 23 + 6 = 3 6 29 9 23 + 2 = 25 3 2 5 23 + 4 = 27 3 4 7

Have a try 5＋4＝ 92＋4＝ 96 9 25＋4＝ 73＋3＝ 35＋4＝ 0＋37＝ 29 76 65＋4＝ 6＋42＝ 5＋4＝ 92＋4＝ 25＋4＝ 73＋3＝ 35＋4＝ 0＋37＝ 65＋4＝ 6＋42＝ 9 96 29 76 39 37 69 48

challenge + 5 = 9 The number behind the is ( ). ① 4 ② 5 ③ 9

challenge 5 + 3 = 9 The number behind the is ( ). ① 4 ② 5 ③ 9

31+2= 31+5= 31+6= 31+20= 31+50= 31+60=