Mom took 100 yuan to go shopping in the supermarket. She bought two bags of rice at 30.6 yuan each and 0.8 kg of meat at 26.5 yuan each. The remaining money is enough to buy a box of eggs from 10 yuan, but not enough to buy a box of eggs from 20 yuan.

Calculate the formula according to the meaning of the question:

30.6×2+26.5×0.8

≈30×2+26× 1

=60+26

=86

100-86= 14

20> 14> 10

So the money left is enough for 10 yuan to buy a box of eggs, but not enough for 20 yuan to buy a box of eggs.

Calculation rules of multiplication:

Number alignment: starting from the right, multiply the first factor by the number on each bit of the second factor, and the end of the number will be aligned with which bit of the second factor; Multiply two complementary digits with the same head and the same tail.

This kind of topic has the same ten digits, and the single digits add up to 10. The calculation formula of this kind of questions is: after a head is added with 1, the head is multiplied by the head and the tail is multiplied by the tail.