First of all, it needs to be clear that scores can be divided into two categories: first, scores can be divided into finite decimals (the simplest fraction, where only factors 2 and 5 can be divided into finite decimals), such as 8=2×2×2, 25=5×5, etc. ); One is that fractions cannot be converted into effective decimals, such as 6=2×3, 12=2×2×3, etc.

Because the denominators of commonly used fractions are not very large, there are only a few denominators that can be converted into finite decimals: 2, 4, 5, 8, 10, 16, 20, 25, 50, 64, etc. The simplest fraction, commonly used denominator is 2, 4, 5, 8, you should study hard, which can greatly improve your calculation speed. 1/2=0.5 1/4=0.25 3/4=0.75 1/5=0.2 2/5=0.4 3/5=0.6 4/5=0.8 1/8=0. 125 3/8=0.375 5/8=0.625 7/8=0.875。 In fact, these interactions are very regular. Just make a little effort!

Fractional decimals with a denominator of 20 can be directly converted into decimals as long as the numerator and denominator are magnified 5 times at the same time and the component mother is 100.

Fractional decimals with a denominator of 25 can be directly converted into decimals as long as the numerator and denominator are magnified four times at the same time and the component mother is 100.

Some of them cannot be converted into finite decimals:1/3 ≈ 0.3331/6 ≈ 0.167 5/6 ≈ 0.833.

The rest is not commonly used, you can use molecular division and denominator calculation!

I hope it helps you, and I wish you better and better! ! !