Round to the nearest ten
Round to the nearest hundred
Ballpark estimate the sum
Ballpark estimate the difference
100
23
20
100
890
900
100
43+26=
40+30=70 43+26=69
100
63-37=
60-40=20 63-37=26
200
57
60
200
147
100
200
90+37=
90+40=130 90+37=127
200
54-22=
50-20=30 54-22=32
300
476
480
300
555
600
300
172+109=
170+110= 280 172+109=281
300
145-56=
150-60=90 145-56=89
400
923
920
400
451
500
400
205+406
200+400=600 205+406= 611
400
283-256=
280-260= 20 283-256= 27
500
178
180
500
555
600
500
769+445=
800+400=1,200 769+445=1,214
500
778-356=
780-360=420 778-356=422
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