Standardized Test question

[bdunham53]

The following question was in a standardized test review. Without the use of a calculator I am not certain how to solve it.

How many digits are in the standard numeral for 2^31 x 5^27?

Using a calculator I get 1.6x10^28 which means there are 29 digits. My students cannot use a calculator on the standardized test.

Help, plesae.

 

[Deleted member 4993]

The following question was in a standardized test review. Without the use of a calculator I am not certain how to solve it.

How many digits are in the standard numeral for 2^31 x 5^27?

Using a calculator I get 1.6x10^28 which means there are 29 digits. My students cannot use a calculator on the standardized test.

Help, plesae.

Hint:

2[sup:1cr1pm92]27[/sup:1cr1pm92] * 5[sup:1cr1pm92]27[/sup:1cr1pm92] = 10[sup:1cr1pm92]27[/sup:1cr1pm92] ... how many digits is that

Now you need multiply that by 2[sup:1cr1pm92]4[/sup:1cr1pm92] (= 16) .... How many total digits would that get you?

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