1998 CEMC Gauss (Grade 7) Problems/Problem 2: Difference between revisions
Coolmath34 (talk | contribs) Created page with "== Problem == The number <math>4567</math> is tripled. The ones digit (units digit) in the resulting number is <math>\text{(A)}\ 5 \qquad \text{(B)}\ 6 \qquad \text{(C)}\ 7..." |
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<math>\text{(A)}\ 5 \qquad \text{(B)}\ 6 \qquad \text{(C)}\ 7 \qquad \text{(D)}\ 3 \qquad \text{(E)}\ 1</math> | <math>\text{(A)}\ 5 \qquad \text{(B)}\ 6 \qquad \text{(C)}\ 7 \qquad \text{(D)}\ 3 \qquad \text{(E)}\ 1</math> | ||
== Solution == | == Solution 1== | ||
Multiply: <math>4567 \cdot 3 = 13701.</math> The units digit is the rightmost digit, which is 1. | Multiply: <math>4567 \cdot 3 = 13701.</math> The units digit is the rightmost digit, which is 1. | ||
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-edited by coolmath34 | -edited by coolmath34 | ||
== Solution 2== | |||
The units digit of a product only depends on the units digits of the numbers being multiplied, which reduces the problem down to <math>7 \cdot 3 = 21</math>, meaning that the units digit is 1 and the answer is <math>\boxed{E}</math>. | |||
Latest revision as of 15:14, 15 June 2022
Problem
The number 
is tripled. The ones digit (units digit) in the resulting number is
Solution 1
Multiply: 
The units digit is the rightmost digit, which is 1.
The answer is 
-edited by coolmath34
Solution 2
The units digit of a product only depends on the units digits of the numbers being multiplied, which reduces the problem down to 
, meaning that the units digit is 1 and the answer is 
.
