1. Tính nhẩm:
a]
\[\eqalign{& 27 \times 10 = \ldots\cr
& 86 \times 10 = \ldots\cr
& 358 \times 10 = \ldots\cr} \] \[\eqalign{
& 72 \times 10 = \ldots\cr
& 103 \times 10 = \ldots\cr
& 1977 \times 100 =\ldots \cr}\] \[\eqalign{
& 14 \times 1000 = \ldots\cr
& 452 \times 1000 = \ldots\cr
& 300 \times 1000 = \ldots\cr} \]
b]
\[\eqalign{
& 80:10 = \ldots\cr
& 300:10 = \ldots\cr
& 2000:10 = \ldots\cr} \]
\[\eqalign{
& 400:100 = \ldots \cr
& 4000:100 = \ldots \cr
& 40000:100 = \ldots \cr} \]
\[\eqalign{
& 6000:1000 = \ldots \cr
& 60000:1000 = \ldots \cr
& 600000:1000 = \ldots \cr} \]
c]
\[\eqalign{
& 64 \times 10 = \ldots \cr
& 640:10 = \ldots \cr} \]
\[\eqalign{
& 32 \times 100 = \ldots \cr
& 3200:100 = \ldots \cr} \]
\[\eqalign{
& 95 \times 1000 = \ldots \cr
& 95000:1000 = \ldots \cr} \]
2. Tính:
a]
\[\eqalign{
& 63 \times 100:10 = \ldots \ldots \cr
& \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,= \ldots \ldots \cr} \]
b]
\[\eqalign{
& 960 \times 1000:100 = \ldots \ldots \cr
& \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \ldots \ldots \cr} \]
c]
\[\eqalign{
& 79 \times 100:10 = \ldots \ldots \cr
& \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \ldots \ldots \cr} \]
d]
\[\eqalign{
& 90000:1000 \times 10 = \ldots \ldots \cr
& \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \ldots \ldots \cr} \]
3. Viết số thích hợp vào chỗ chấm:
a] 160 = 16 ×
4500 = × 100
9000 = 9 ×
c]70000 = × 1000
70000 = ×100
70000 = ×10
b] 8000 = × 1000
800 = ×100
80 = × 10
d]2020000 = × 10000
2020000 = 2020 ×
2020000 =× 10
Bài giải:
1.
a]
\[\eqalign{
& 27 \times 10 = 270; \cr
& 86 \times 10 = 860; \cr
& 358 \times 10 = 3580; \cr} \]
\[\eqalign{
& 72 \times 10 = 720; \cr
& 103 \times 10 = 10300; \cr
& 1977 \times 100 = 197700; \cr} \]
\[\eqalign{
& 14 \times 1000 = 14000 \cr
& 452 \times 1000 = 452000 \cr
& 300 \times 1000 = 300000 \cr} \]
b]
\[\eqalign{
& 80:10 = 8; \cr
& 300:10 = 30; \cr
& 2000:10 = 200; \cr} \]
\[\eqalign{
& 400:100 = 4 \cr
& 4000:100 = 40 \cr
& 40000:100 = 400 \cr} \]
\[\eqalign{
& 6000:1000 = 6 \cr
& 60000:1000 = 60 \cr
& 600000:1000 = 600 \cr} \]
c]
\[\eqalign{
& 64 \times 10 = 640; \cr
& 640:10 = 64; \cr} \]
\[\eqalign{
& 32 \times 100 = 3200; \cr
& 3200:100 = 32; \cr} \]
\[\eqalign{
& 95 \times 1000 = 95000 \cr
& 95000:1000 = 95 \cr} \]
2.
a]
\[\eqalign{
& 63 \times 100:10 = 6300:10 \cr
& \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 630 \cr} \]
b]
\[\eqalign{
& 960 \times 1000:100 = 960000:100 \cr
& \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 9600 \cr} \]
c]
\[\eqalign{
& 79 \times 100:10 = 7900:10 \cr
& \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 790 \cr} \]
d]
\[\eqalign{
& 90000:1000 \times 10 = {\mkern 1mu} {\mkern 1mu} 90 \times 10 \cr
& \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 900 \cr} \]
3.
a] 160 = 16 × 10
4500 = 45 × 100
9000 = 9 ×1000
c]70000 = × 1000
70000 = ×100
70000 = ×10
b] 8000 = 8× 1000
800 = 8×100
80 = 8× 10
d]2020000 = 202 × 10000
2020000 = 2020 ×1000
2020000 =202000 × 10