17. Calculați și apoi completați spațiile punctate:
a) 20 m + 2 dam + 31 dm =... dm;
b) 36 cm + 120 mm-2 dm =... cm;
c) 148 hm - 1 km + 240 dam + 50 m =... dam;
d) 76 dam - 25 m + 1800 dm =... m;
e) 2600 cm + 17000 mm - 15 m =... dm;
f) 640 hm + 24 dam - 150 m =... dam.
Răspunsuri la întrebare
Răspuns:
Explicație pas cu pas:
a) 20 m + 2 dam + 31 dm =
= 20 dm + 200 dm + 31 dm = 251 dm
1 m = 10 dm
20 m x 10 = 20 dm
1 dam = 10 m = 100 dm
2 dam x 100 = 200 dm
b) 36 cm + 120 mm-2 dm =
= 36 cm + 12 cm - 20 cm =
= 48 cm - 20 cm = 28 cm
1 cm = 10 mm
120 mm : 10 = 12 cm
1 dm = 10 cm
2 dm x 10 = 20 cm
c) 148 hm - 1 km + 240 dam + 50 m =
= 1480 dam - 100 dam + 240 dam + 5 dam =
= 1380 dam + 240 dam + 5 dam =
= 1625 dam
1 hm = 10 dam
148 hm x 10 = 1480 dam
1 km = 10 hm = 100 dam
1 dam = 10 m
50 m : 10 = 5 dam
d) 76 dam - 25 m + 1800 dm =
= 760 m - 25 m + 180 m =
= 735 m + 180 m =
= 915 m
1 dam = 10 m
76 dam x 10 = 760 m
1 m = 10 dm
1800 dm : 10 = 180 m
e) 2600 cm + 17000 mm - 15 m =
= 260 dm + 170 dm - 150 dm =
= 430 dm - 150 dm =
= 280 dm
1 dm = 10 cm = 100 mm
2600 cm : 10 = 260 dm
17000 mm : 100 = 170 dm
1 m = 10 dm
15 m x 10 = 150 dm
f) 640 hm + 24 dam - 150 m =
= 6400 dam + 24 dam - 15 dam =
= 6424 dam - 15 dam =
= 6409 dam
1 hm = 10 dam
640 hm x 10 = 6400 dam
1 dam = 10 m
150 m : 10 = 15 dam