Question

Calculează rapid, după modelul dat: Model: 36 +84 = (30+6) + 84 = 30 + (6 +84) = 30 +90 = 120. a) 81 +99; b) 147 + 253; c) 1473 +2517; d) 23 874 + 1116.​

Answer 1

Răspuns:

a) 81 +99=(80+1)+99=80+(1+99)=80+100=180

b) 147 + 253=(100+40+7)+253=(100+40)+(7+253)=140+260=400

c) 1473 +2517=(1000+400+70+3)+2517=

(1000+400+70)+(2517+3)=1470+2520=3990

d) 23 874 + 1116=(20000+3000+8000+70+4)+1116=

(20000+3000+8000+70)+(1116+4)=23870+1120=24990