8,56dm2=0,0856m20,42m2=42dm22,5km2=0,0000025m21,8ha=0,000008m20,001ha=0,0000001m20,03ha=0,000003m20,48km=480m
Bài 2:
a)20,11 < 20,15 < 20,12
b)0,0004 < 0,00045 < 0,0005
Bài 3:
a)
234 × 76 + 117 × 48 + 234 × 425
=234 (76 + 425) +117 × 48
=234 × 501 + 117 × 48
=117 × 501 × 2 + 117 × 48
=117 (501 × 2 + 48)
=117 (1050)
=117000 + 5850
=122850
b)
1 + 5 + 9 +...+ 193 + 197
=(1 + 197) + (5 + 193) +...
=198 × 25
=4950
Bài 4:
8,56dm2=0,0856m2
0,42m2=42dm2
2,5km2=0,0000025m2
1,8ha=0,000018m2
0,001ha=0,0000001m2
0,03ha=0,000003m2
0,48km=480m