## BEATCALC:  Beat the Calculator!

Back to Calculation Tips & Tricks

 From B. Lee Clay

Squaring Numbers

1. beginning with 1
2. beginning with 5
3. beginning with 9
4. ending in 1
5. ending in 2
6. ending in 3
7. ending in 4
8. ending in 5
9. ending in 6
10. ending in 7
11. ending in 8
12. ending in 9
17. in the 20's
18. in the 30's
19. in the 40's
20. in the 50's
21. in the 60's
22. in the 70's
23. in the 80's
24. in the 100's
25. in the 200's
26. in the 300's
27. in the 400's
28. in the 500's
29. in the 600's
30. in the 700's
31. between 800-810
32. in the 900's
33. between 1000-1100
34. between 2000-2099
35. between 3000-3099
36. between 4000-4099
37. between 5000-5099
38. between 6000-6099
39. between 7000-7099
40. 3's and final 1
41. 3's and final 2
42. 3's and final 4
43. 3's and final 5
44. 3's and final 6
45. 3's and final 7
46. 3's and final 8
47. 3's and final 9
48. 6's and final 1
49. 6's and final 2
50. 6's and final 3
51. 6's and final 4
52. 6's and final 5
53. 6's and final 7
54. 6's and final 8
55. 6's and final 9
56. 9's and final 1
57. 9's and final 2
58. 9's and final 3
59. 9's and final 4
60. 9's and final 5
61. 9's and final 6
62. 9's and final 7
63. 9's and final 8
64. 1 and repeating 3's
65. 1 and repeating 6's
66. 1 and repeating 9's
67. 2 and repeating 3's
68. 2 and repeating 6's
69. 2 and repeating 9's
70. 3 and repeating 6's
71. 3 and repeating 9's
72. 4 and repeating 3's
73. 4 and repeating 6's
74. 4 and repeating 9's
75. 5 and repeating 3's
76. 5 and repeating 6's
77. 5 and repeating 9's
78. 6 and repeating 3's
79. 6 and repeating 9's
80. 7 and repeating 3's
81. 7 and repeating 6's
82. 7 and repeating 9's
83. 8 and repeating 3's
84. 8 and repeating 9's
85. 9 and repeating 3's
86. 9 and repeating 6's
87. 6-digits repeating
88. 2 rep./sq. of 1 digit

Multiplying Numbers

Dividing Numbers

Subtracting Numbers

Finding Percents

Calculation
Practice Exercises

Full List

### Squaring numbersbetween 7000 and 7099

1. Choose a number between 7000 and 7099.
2. The first three digits are: 4 9 0 _ _ _ _ _
3. The next two digits are 4 times the last two digits,
with zero added: _ _ _ X X _ _
4. For the last three digits, square the last two digits in the number chosen (insert zeros when needed):
_ _ _ _ _ X X X

#### Example:

1. If the number to be squared is 7004:
2. The first three digits are: 4 9 0 _ _ _ _ _
3. The next two digits are 4 times the last two, with zero added:
4 × 4 = 16; 16 + 40 = 56: _ _ _ 5 6 _ _ _
4. For the last three digits, square the last two:
4 × 4 = 16: _ _ _ _ 0 1 6
5. So 7004 × 7004 = 49,056,016.

See the pattern?

For numbers greater than 7007, reverse the order:

1. If the number to be squared is 7025:
2. For the last three digits, square the last two:
25 × 25 = 625: _ _ _ _ 6 2 5
3. For the middle two digits, add zero to the last two,
then add 4 times the last two:
250 + 4 × 25: 250 + 100 = 350 (keep carry):
_ _ _ 5 0 _ _ _
4. The first three digits are 490 + the carry:
490 + 3 = 493: 4 9 3 _ _ _ _ _
5. So 7025 × 7025 = 49,350,625.