Question

How many numbers between 30 and 60 contain:
a) figure 4;

b) two identical digits;

c) the digits 1 or 8?

a) Determine the shape numbers a B C , knowing a B C = 3 · 100 + 7 · 10 + 9.
b) Determine the digits a , b , c , knowing that 324 = a · 100 + b · 10 + c .
c) Determine the digits a , b , c , d , knowing thata 3 c 4= 5 · 1,000 + b · 100 + 7 · 10 + d .
a) How many digits were used to number a 320-page book?
b) 612 digits were used to number the pages of a book. How many pages does the book have?

Answer 1

Answer:

28

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Answer 2

Answer:

28...................