378+527+23 (the positive operation of addition and association law makes the last two numbers add up to an integer of 100)

576+(24+ 187) (the inverse operation of the addition rate makes the first two numbers add up to an integer)

167+289+33 (additive commutative law, exchange the last two numbers, and then add them to the first number by the law of association to make up an integer).

567+( 187+24) (remove brackets first, then exchange, and finally merge)

58+392+42+6 1 (exchange first, then merge)

546+20 1 (divide 20 1 by the sum of 200+ 1 first, and then use the additive associative law).

546+ 199 (divide 199 by the difference of 200- 1 and remove the brackets)

Second, subtraction.

559- 145-255 (the nature of subtraction, minus the sum of two numbers)

487-( 187+ 126) (the inverse operation of subtraction, successively subtracting these two numbers, 487 and 187 have the same mantissa, and 187 is subtracted first).

442- 103- 142(442 and 142 have the same mantissa, so 142 should be subtracted first, so there are two meiotic exchange positions).

8755-(2 187+755) uses the inverse operation of subtraction first, and then exchanges.

546-20 1 first split 20 1 into (200+ 1), and then use 546-(200+ 1). The nature of subtraction is equal to 546-200- 1.

546- 199 first split 199 into (200- 1), then use 546-(200- 1), and remove the symbol with the minus sign before the brackets, which is equal to 546-200+ 1.

Comprehensive:

487-( 187- 126) minus sign is used before brackets, and the rule of changing the sign after removing brackets is equal to 487- 187+ 126.

487+ 126- 187 adopts the exchange method, and the last two digits are exchanged. When exchanging, move with the symbol.

547+358+342-347 should be exchanged before being combined. When exchanging, you should use symbols to move the combination in pairs.

85- 17+ 15-33 are exchanged and then combined. When exchanging, you should use symbols to move the combination in pairs.

Third, multiplication.

457×2×5 Multiplies the last two numbers to form an integer by using the positive operation of the multiplicative associative law.

125×(80×7) Multiplies the first two numbers to form an integer by the inverse operation of the multiplicative associative law.

125×7×80 uses the multiplication exchange law, and then 125 and 80 are multiplied to form an integer thousand.

125×(30×8) removes the brackets by the inverse operation of the multiplicative associative law, and then multiplies 125 and 8 by the commutative law to get an integer thousand.

125×(80+8) Multiply 125 by 80 and 8 respectively, and then add them.

125×(80-8) Multiply 125 by 80 and 8 respectively, and then subtract.

38×62+38×38 Using the inverse operation of multiplication and division, the same factor 38 is extracted first, and then the remaining 62 and 38 are added.

65×99+65 First write 65 as 65× 1, then use the inverse operation of multiplication and division to extract the same factor 65 as * *, and then add the remaining 99 and 1.

65× 10 1-65 Write 65 as 65× 1 first, then use the inverse operation of multiplication and division to extract the same factor as * * 65, and then subtract the remaining 10 1 and 1.

38× 10 1 divide 10 1 by (100+ 1), and then multiply 38 by 100 and/kloc-0 respectively by multiplication and division.

38×99 first splits 99 into (100- 1), and then multiplies 38 with 100 and 1 respectively and subtracts them by the multiplication distribution law.

125×32×25 First, split 32 into (4×8). Then multiply 125 and 8 by 25 and 4, and then multiply the two products.

125×88 first splits 88 into (80+8), then multiplies 125 with 80 and 8 respectively, and then adds them by using the multiplication and distribution law.

You can also split 88 into (1 1×8), then multiply 125 by 8 and then multiply the product by 1 1.

Comprehensive:

79×25+22×25-25 Using the inverse operation of the multiplication and division rule, the same factor 25 is extracted first, and then the remaining 79, 22 and 25 are added and subtracted.

67× 2 1+18× 21+15× 21The same factor of 21is extracted first, and then the remaining 67,/kloc-0 are extracted.

125× 15×8×4 Multiply 125 by 8, multiply 15 by 4, and then multiply the two products.

Fourth, division.

3500÷25÷4 Use the nature of division to divide by the product of two numbers.

3500÷(35×25) Using the inverse operation of the division property, the product of dividing by two numbers is equal to dividing by these two numbers continuously.

3500÷(25×35) uses the inverse operation of division property to divide these two numbers continuously, and then exchange the two divisors.

800÷ 16 First, split 16 into (8×2), and then use the nature of division to divide the product of two numbers into two numbers.

3500÷25÷35 divided by two divisor swap positions.

Comprehensive:

150×24÷50 exchanges the last two digits, and moves with the symbol when exchanging.