TÍNH NHẨM CỘNG TRỪ NHÂN CHIA KIỂU ANH

ADDING

Put the larger number first and count on:

6 + 29 = 29 + 6 count on from 29

Count on in tens

55 + 24 = 55, 65, 75 + 4

Partition numbers and recombine:

37 + 15 = 37 + 3+ 12 = 40 + 12

Use near numbers and adjust:

27 + 19 = 27 + 20 – 1 = 47 – 1

Break both numbers into tens and units

24 + 59 = 20 + 50 + 4 + 9 = 70 + 13 = 70 + 10 + 3 = 80 + 3 (nếu trò tạm thì đến 70 + 13 còn ẹ quá thì đến 80 + 3)

Use doubles:

38 + 37 = double 40, subtract 2, subtract 3

Use combinations of these

64 + 27 = 64 + 20 + 7 = 84 + 7 = 84 + 6 + 1

SUBTRACTING

Count on from smaller number:

23 – 18 count on from 18 to 20 and from 20 to 23

Count on in ones and tens

82 – 59 = 59 to 60, 70, 80 to 82

Partition numbers:

94 – 43 = 94 – 40 – 3 = 54 – 3

Use near numbers and adjust

43 – 19 = 43 – 20 + 1 = 23 + 1

Đây là cách trừ của Anh và VN nhé, chị xem lại há


MULTIPLYING

To multiply by 2, split into tens and units and double:

2 x 36 is double 30 plus double 6

To multiply by 4, double and double again

4 x 25 is double 25 which is 50 and double again which is 100

To multiply by 5, multiply by ten and halve:

5 x 14 is half of 10 x 14 which is half of 140

To multiply by 15, multiply by 10, halve it and add the two together:(

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Use near number and adjust

3 x 19 = (3 x 20) – 3 = 60 – 3 = 57

Split numbers (use distribute law):

3 x 56 = 3 x (50 + 6) = (3 x 50) + (3 + 6) = 150 + 18

DIVIDING

To divide by 2, split and halve:

76 : 2 = half of 60 and half of 16

To divide by 4, halve and halve again

28: 4 = half of 28 which is 14 and half of 14 is 7

Break down into factors

90 : 6 = (90:3): 2 = 30 :2 = 15

Nuôi Dạy Con: Mình viết hai dấu chấm cho phép chia như vậy là bọn Anh nó không hiểu, những ngày đầu mới qua Anh mình cứ hay quên giờ thì nhớ gạch ngang giữa hai dấu chấm rồi.

Đây là hình mình họa cho dấu chia và cách chia luôn bạn nhé

(Blog Lienrom)

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