Toán học

Câu 1, 2, 3 trang 61 Vở bài tập (SBT) Toán lớp 4 tập 1

Nội dung bài giảng

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