Find all two-digit numbers whose sum of digits does not change after multiplicat

a) Add one digit to the left and right of the number 15 so that the resulting nu

b) Add one digit to the left and right of the number 10 so that you get a number

Find the largest natural number divisible by 36, the notation of which involves

On the board it is written: 645*7235. Replace the asterisk with a number so that

Fill the digits to make divisible by 45

In the country of Anchuria, the following denominations of banknotes are in circ

a) Find a two-digit number whose first digit is equal to the difference between

Is it true that if you write the digits of any integer in reverse order, then th

Find all two-digit numbers whose sum of digits does not change after multiplicat

Is there a natural number whose product of digits equals 528?

How many digits are in the number 11...11 if it is divisible by 999,999,999?

The numbers were rearranged and a number was obtained that was 3 times smaller t

The sum of its digits was added to the number. The sum of its digits was added t

For each of the numbers from 1 to 1,000,000,000, the sum of its digits was calcu

a) Prove that numbers of the form aa, abcabc, abcdeabcde are divisible by

(And in general, prove that if we assign the same number to an arbitrary number

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