 # Multiplication: Shortcuts for 9, 99 and 999

In this worksheet, students develop their mental arithmetic skills by using shortcuts to help them multiply quickly and accurately. Key stage:  KS 3

Curriculum topic:   Number

Curriculum subtopic:   Use Four Operations for All Numbers

Difficulty level:   ### QUESTION 1 of 10

Checking your results by doing an equivalent operation is a valuable skill to learn.

Look carefully at the following to understand the method used when multiplying by numbers such as 9, 99 or 999.

11 × 9 = 11 × (10 - 1) = 110 - 11 = 99

521 × 9 = 521 × (10 - 1) = 5210 - 521 = 4689

19 × 99 = 19 × (100 - 1) = 1900 - 19 = 1881

17 × 999 = 17 × (1000 - 1) = 17000 - 17 = 16983

For the following calculation, work out the values of A, B and C.

91 × 9 = 91 × (10 - 1) =
 A
-
 B
=
 C

 A B C 910 91 819

For the following calculation, work out the values of A, B and C.

47 × 9 = 47 × (10 - 1) =
 A
-
 B
=
 C

 A B C 47 423 470

For the following calculation, work out the values of A, B and C.

73 × 999 = 73 × (1000 - 1) =
 A
-
 B
=
 C

 A B C 72927 73000 73

For the following calculation, work out the values of A, B and C.

20 × 999 = 20 × (1000 - 1) =
 A
-
 B
=
 C

 A B C 20 20000 19980

For the following calculation, work out the values of A, B and C.

21 × 99 = 21 × (100 - 1) =
 A
-
 B
=
 C

 A B C 21 2079 2100

For the following calculation, work out the values of A, B and C.

70 × 9 = 70 × (10 - 1) =
 A
-
 B
=
 C

 A B C 70 630 700

For the following calculation, work out the values of A, B and C.

97 × 999 = 97 × (1000 - 1) =
 A
-
 B
=
 C

 A B C 97 97000 96903

For the following calculation, work out the values of A, B and C.

60 × 9 = 60 × (10 - 1) =
 A
-
 B
=
 C

 A B C 600 60 540

For the following calculation, work out the values of A, B and C.

14 × 999 = 14 × (1000 - 1) =
 A
-
 B
=
 C

 A B C 14 14000 13986

For the following calculation, work out the values of A, B and C.

213 × 99 = 213 × (100 - 1) =
 A
-
 B
=
 C

 A B C 21300 21087 21 213
• Question 1

For the following calculation, work out the values of A, B and C.

91 × 9 = 91 × (10 - 1) =
 A
-
 B
=
 C

 A B C 910 91 819
• Question 2

For the following calculation, work out the values of A, B and C.

47 × 9 = 47 × (10 - 1) =
 A
-
 B
=
 C

 A B C 47 423 470
• Question 3

For the following calculation, work out the values of A, B and C.

73 × 999 = 73 × (1000 - 1) =
 A
-
 B
=
 C

 A B C 72927 73000 73
• Question 4

For the following calculation, work out the values of A, B and C.

20 × 999 = 20 × (1000 - 1) =
 A
-
 B
=
 C

 A B C 20 20000 19980
• Question 5

For the following calculation, work out the values of A, B and C.

21 × 99 = 21 × (100 - 1) =
 A
-
 B
=
 C

 A B C 21 2079 2100
• Question 6

For the following calculation, work out the values of A, B and C.

70 × 9 = 70 × (10 - 1) =
 A
-
 B
=
 C

 A B C 70 630 700
• Question 7

For the following calculation, work out the values of A, B and C.

97 × 999 = 97 × (1000 - 1) =
 A
-
 B
=
 C

 A B C 97 97000 96903
• Question 8

For the following calculation, work out the values of A, B and C.

60 × 9 = 60 × (10 - 1) =
 A
-
 B
=
 C

 A B C 600 60 540
• Question 9

For the following calculation, work out the values of A, B and C.

14 × 999 = 14 × (1000 - 1) =
 A
-
 B
=
 C

 A B C 14 14000 13986
• Question 10

For the following calculation, work out the values of A, B and C.

213 × 99 = 213 × (100 - 1) =
 A
-
 B
=
 C

 A B C 21300 21087 21 213
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