[Speed Math] MULTIPLYING 4-DIGIT NUMBERS NEAR A BASE NUMBER

Here’s an example of a SPEED MATH shortcut for MULTIPLYING 4-DIGIT NUMBERS NEAR A BASE NUMBER : (Mul) NrB4 from the MULTIPLICATION category.

When can I use this method?

For multiplying any 4-digit number with another 4-digit number such that the numbers are relatively near each other.

You may also use this method to multiply numbers a little farther away from each other as long as their differences from the Base number are easy to multiply.

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Download Practice sheet for MULTIPLYING 4-DIGIT NUMBERS NEAR A BASE NUMBER

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Notes –

1. When selecting a Base number, prefer a number that is near the multiplier and multiplicand as well as it should be easy to multiply with (prefer round numbers).
2. This method uses the concept (B + a) (B + b) = [(B + a) + b] + ab or [(B + b) + a] + ab, where ‘(B + a)’ and ‘(B + b)’ are numbers near a Base number ‘B’ and ‘a’ and ‘b’ are the respective differences.
3. Whenever the number is more than the Base number, the difference is written as positive (+ve).
4. Whenever the number is less than Base Number, the difference is written as negative (-ve).
5. When both numbers are either less or more than Base Number, you add the product of differences.
6. When one number is more than Base number and another less than Base number, you subtract the product of differences.

Related Shortcuts –

Multiplying 2-digit Numbers near a Base Number: (Mul) NrB2
Multiplying 3-digit Numbers near a Base Number: (Mul) NrB3
Multiplying Numbers near different Base Numbers: (Mul) NrBpBs
Multiplying Numbers using Nearby Method: (Mul) NxM(Nr)

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