Wrong Way Round

Ron Gwairown always writes numbers down back to front. At school, he was once asked to do the following calculation:

Ron Gwairown

14 x 82

In his exercise book Ron wrote down:

41 x 28

1. What answer did he get?

2. What answer should he have got?

3. Investigate other pairs of calculations of this type? What can you discover?

A Mathematics Lesson Starter Of The Day


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Topics: Starter | Arithmetic | Investigations | Place Value

  • LRH, MCS Brackley
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  • I used this with a top set year 9. We collated our results after about 15 minutes and the students found an explanation using multiplication grids for a general rule linking all the pairs they found. A great success! More like this, please.
  • Y6, Tickhill St Mary's
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  • Question 3 gives away the answer to question 2!
  • Mrs Rowe, Edenham High
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  • I was warned that it was quite hard. Set for top year 8's lasted the majority of our first lesson of the year.
  • KS3 Form Teacher, West Midlands
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  • This starter was very good for engaging a multi-ethnic y7-9 form group - to a certain extent, the older, more knowledgeable kiddies were able to address the queries of the little ones! Can be very suitable for a class whose English is perhaps not the best. A nice way of revising long multiplication for those who need it and an interesting quirk of mathematics for those who don't. Easy 20-ish minutes of class-wide engagement.

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This starter has scored a mean of 3.3 out of 5 based on 230 votes.


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Answers

11 x 11
11 x 22
11 x 33
11 x 44
11 x 55
11 x 66
11 x 77
11 x 88
11 x 99
12 x 21
12 x 42
12 x 63
12 x 84
13 x 31
13 x 62
13 x 93
14 x 41
14 x 82
15 x 51
16 x 61
17 x 71
18 x 81
19 x 91
21 x 12
21 x 24
21 x 36
21 x 48
22 x 11
22 x 22
22 x 33
22 x 44
22 x 55
22 x 66
22 x 77
22 x 88
22 x 99
23 x 32
23 x 64
23 x 96
24 x 21
24 x 42
24 x 63
24 x 84
25 x 52
26 x 31
26 x 62
26 x 93
27 x 72
28 x 41
28 x 82
29 x 92
31 x 13
31 x 26
31 x 39
32 x 23
32 x 46
32 x 69
33 x 11
33 x 22
33 x 33
33 x 44
33 x 55
33 x 66
33 x 77
33 x 88
33 x 99
34 x 43
34 x 86
35 x 53
36 x 21
36 x 42
36 x 63
36 x 84
37 x 73
38 x 83
39 x 31
39 x 62
39 x 93
41 x 14
41 x 28
42 x 12
42 x 24
42 x 36
42 x 48
43 x 34
43 x 68
44 x 11
44 x 22
44 x 33
44 x 44
44 x 55
44 x 66
44 x 77
44 x 88
44 x 99
45 x 54
46 x 32
46 x 64
46 x 96
47 x 74
48 x 21
48 x 42
48 x 63
48 x 84
49 x 94
51 x 15
52 x 25
53 x 35
54 x 45
55 x 11
55 x 22
55 x 33
55 x 44
55 x 55
55 x 66
55 x 77
55 x 88
55 x 99
56 x 65
57 x 75
58 x 85
59 x 95
61 x 16
62 x 13
62 x 26
62 x 39
63 x 12
63 x 24
63 x 36
63 x 48
64 x 23
64 x 46
64 x 69
65 x 56
66 x 11
66 x 22
66 x 33
66 x 44
66 x 55
66 x 66
66 x 77
66 x 88
66 x 99
67 x 76
68 x 43
68 x 86
69 x 32
69 x 64
69 x 96
71 x 17
72 x 27
73 x 37
74 x 47
75 x 57
76 x 67
77 x 11
77 x 22
77 x 33
77 x 44
77 x 55
77 x 66
77 x 77
77 x 88
77 x 99
78 x 87
79 x 97
81 x 18
82 x 14
82 x 28
83 x 38
84 x 12
84 x 24
84 x 36
84 x 48
85 x 58
86 x 34
86 x 68
87 x 78
88 x 11
88 x 22
88 x 33
88 x 44
88 x 55
88 x 66
88 x 77
88 x 88
88 x 99
89 x 98
91 x 19
92 x 29
93 x 13
93 x 26
93 x 39
94 x 49
95 x 59
96 x 23
96 x 46
96 x 69
97 x 79
98 x 89
99 x 11
99 x 22
99 x 33
99 x 44
99 x 55
99 x 66
99 x 77
99 x 88
99 x 99


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