Multiplying by 858
To multiply a multiple of 7 by 858, perform the following:
• Divide the number by 7.
• Multiply the number by 6.
• Write the result on the right, using three digits. Then
write the result on the left.
Example:
28 × 858 =
• 28 ÷ 7 = 4
• 4 × 6 = 24
• Write 024 as 24 is the result and you must use
three-digits. Then write the 20 on the left. The final answer is
24024.
28 × 858 = 24024.
Example:
91 × 858 =
• 91 ÷ 7 = 13
• 13 × 6 = 78
• Write 078 on the right (using three digits). Then write
78 on the left. The final answer is 78078.
91 × 858 = 78078.
Note: This trick works because  .
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