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Algebra Difficulty 1.9 Junior Find the answer

If the number of zeros in the integer equal to (10100)imes(10010)(10^{100}) imes (100^{10}) is sought, what is this number?

A number or a short expression. Spacing and $ signs are ignored.

Solution

Since 100=102100=10^{2}, then 10010=(102)10=1020100^{10}=(10^{2})^{10}=10^{20}. Therefore, (10100)imes(10010)=(10100)imes(1020)=10120(10^{100}) imes (100^{10})=(10^{100}) imes (10^{20})=10^{120}. When written out, this integer consists of a 1 followed by 120 zeros.

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