LazyMaths.com

Here’s an example of a SPEED MATH shortcut for MULTIPLYING NUMBERS WITH FIRST DIGITS SUM 1000 : (Mul) F1000dx from the MULTIPLICATION category.

When can I use this method?

For multiplying any 4-digit number with another 4-digit number such that the sum of the initial digits of the multiplier and multiplicand = 1000 and the remaining digits of multiplier are same as that of the multiplicand.

For multiplying any 5-digit number with another 5-digit number such that the sum of the initial digits of the multiplier and multiplicand = 1000 and the remaining digits of multiplier are same as that of the multiplicand.

You cannot use this method to multiply numbers with unequal number of digits, i.e. multiplying a 4-digit number with a 5-digit number.

Speed Math Shortcut - Multiplying Numbers with sum of Initial digits = 1000: Example 1

Title

Speed Math Shortcut - Multiplying Numbers with sum of Initial digits = 1000: Example 1

Title

Speed Math Shortcut - Multiplying Numbers with sum of Initial digits = 1000: Example 2

Title

Speed Math Shortcut - Multiplying Numbers with sum of Initial digits = 1000: Example 3

Title

Speed Math Shortcut - Multiplying Numbers with sum of Initial digits = 1000: Example 4

Title

Speed Math Shortcut - Multiplying Numbers with sum of Initial digits = 1000: Example 5

Download Practice sheet for MULTIPLYING NUMBERS WITH FIRST DIGITS SUM 1000

Notes –

1. Notice the way the common digits are added.
2. When multiplying 4-digit numbers with common last digit, remember to write the RHS of the answer in 2-digit form by prefixing a zero, if the value is single digit, e.g. write ‘9’ as ‘09’.
3. When multiplying 5-digit numbers with last 2 digits common, remember to write the RHS of the answer in 4-digit form by prefixing zero(s), if the value is less than 4-digit, e.g. write ‘9’ as ‘0009’ or ‘21’ as ‘0021’ or ‘121’ as ‘0121’.

Related Shortcuts –

Multiplying Numbers with first digits sum 10: (Mul) F10dx
Multiplying Numbers with first digits sum 100: (Mul) F100dx

We hope this helps you in getting to the answer faster. You can apply this shortcut in the exams and get to the answer before anyone else can.

If you like this
- Share it with your friends

If you know more shortcuts like this
- Share it with us

Want more of these? Click SPEED MATH

Wanna learn from other resources? Head to our MORE MATH page

You can also join OUR CLASSES and learn hundreds of such techniques. Learn to apply them in your exams and even in everyday life! We offer classroom training for SAT, GRE, GMAT and many more exams.

Is this a helpful shortcut? Don’t forget to rate this shortcut

Tell us what you think. How can we improve? Feel free to comment or ask questions. We can be reached at math(at)lazymaths(dot)com