1. Thực hiện phép tính:
a) $96.50+25.400$
$=4800+10000$
$=14800$
b) $125.80+50.20$
$=10000+1000$
$=11000$
c) $640:32+32$
$=20+32$
$=52$
d) $218-180:2:9$
$=218-90:9$
$=218-10$
$=208$
e) $2^{2}.3^{2}-5.23$
$=4.9-5.23$
$=36-115$
$=-79$
f) $5^{2}.2+20:2^{2}$
$=25.2+20.4$
$=50+80$
$=130$
g) $\textrm{10.{420:6+[150-68.2-2^{3}.5)]}}$
$=\textrm{10.{420:6+[150-(68.2-8.5)]}}$
$=\textrm{10.{420:6+[150-(136-40)]}}$
$=\textrm{10.{420:6+(150-96)}}$
$=10.(420:6+54)$
$=10.(70+54)$
$=10.124$
$=1240$
2. Tính nhanh:
a) $32.19+32$
$=32.19+32.1$
$=32.(19+1)$
$=32.20$
$=640$
b) $43.17+29.57+13.43+57$
$=43.17+29.57+13.43+57.1$
$=43.(17+13)+57.(29+1)$
$=43.30+57.30$
$=30.(43+57)$
$=30.100$
$=3000$
c) $1326+538-326-38$
$=(1326-326)+(538-38)$
$=1000+500$
$=1500$
d) $375:25-125:25$
$=(375-125):25$
$=250:25$
$=10$
3. Bài giải:
$=(198.10^{25}):(6.10^{21})$
$=198.10^{25}:6:10^{21}$
$=(198:6).(10^{25}:10^{21})$
$=33.10^{4}$
$=33.10000$
$=330000$
Vậy khối lượng mặt trời gấp 330000 lần khối lượng trái đất