Using the division method, find the HCF of 1,001 and 1,547.

7Correct answerYour answer13Correct answerYour answer77Correct answerYour answer91Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer D

Correct answer: D

$1547 = 1 \times 1001 + 546$ .
$1001 = 1 \times 546 + 455$ .
$546 = 1 \times 455 + 91$ , and $455 = 5 \times 91 + 0$ .
The last non-zero remainder is the HCF: 91.

Worth noting

$1001 = 7 \times 11 \times 13$ and $1547 = 7 \times 13 \times 17$ , so the common part is $7 \times 13 = 91$ . Stopping at 7 or 13 misses the other shared prime.

Concept: HCF by repeated division (Euclid's method)
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Using the division method, find the HCF of 1,001 and 1,547.

Explanation