Mental Mondays #10

This is Mental and Oral starter gives children plenty of opportunities to work with a specific 'times table'.

However the focus is on using a range of strategies to solve mathematical problems. It's also quite fun!

You start off by showing the children times table. However, most of the numbers are replaced by letters.

Here's an example using the 9 Times Table:

G x 9 = KH
M x 9 = 9
T x 9 = FB
B x 9 = WT
F x 9 = BF
MZ x 9 = 9Z
W x 9 = HK
H x 9 = MG
9 x 9 = GM
K x 9 = TW

Not only are most of the numbers replaced by letters but the times table is not in numerical order. The challenge, of course, is for the children to use whatever strategies they feel appropriate to try to identify the 'coded' numbers.

For example, the children may quickly notice that the second line shows M x 9 = 9. Clearly, then M = 1.

This can be proven by looking at the second to the last row, 9 x 9 = GM. Since 9x9 is 81, G = 8 and M = 1.

Now we know about G and M, maybe that will help somewhere else... the next line above shows H x 9 = MG; so now we have learnt that H must be 2.

F x 9 = BF is also a useful line... what number (represented by F) when multiplied by 9 appears in the units (ones) column of the product? Only one number works in this situation: 5, 5 x 9 = 45. So F must be 5, and we have also learnt that B is 4.

If children have some confidence with the 9 times table, and can use a number of problem solving strategies, the completion of this times table should be a fairly rapid affair.

After a few minutes, ask the children to share their findings and to discuss their strategies and their thinking.

Here's the solution:

8 x 9 = 72
1 x 9 = 9
6 x 9 = 54
4 x 9 = 36
5 x 9 = 45
10 x 9 = 90
3 x 9 = 27
2 x 9 = 18
9 x 9 = 81
7 x 9 = 63

A follow-up activity could be to encourage a pair of children to 'encode' a times table for another pair to 'crack'. alternatively, you could simply challenge them to decode one of the following times tables as quickly as they can.

Here are the remaining times tables, should you want to use them you can copy and paste them off of this page. We haven't included the 10x table... maybe you could challenge your children to find out why the 10x table cannot be coded (or decoded) satisfactorily?
 

2 Times Table

E x 2 = T2
D x 2 = TA
R x 2 = A
A x 2 = I
TF x 2 = 2F
T x 2 = 2
W x 2 = E
C x 2 = TF
I x 2 = TE
H x 2 = TI

6 x 2 = 12
7 x 2 = 14
2 x 2 = 4
4 x 2 = 8
10 x 2 = 20
1 x 2 = 2
3 x 2 = 6
5 x 2 = 10
8 x 2 = 16
9 x 2 = 18

3 Times Table

G x 3 = TP
V x 3 = KT
K x 3 = G
A x 3 = TK
TU x 3 = 3U
T x 3 = 3
3 x 3 = S
W x 3 = TW
P x 3 = KA
S x 3 = KV

6 x 3 = 18
7 x 3 = 21
2 x 3 = 06
4 x 3 = 12
10 x 3 = 30
1 x 3 = 03
3 x 3 = 09
5 x 3 = 15
8 x 3 = 24
9 x 3 = 27

4 Times Table

Z x 4 = DA
CR x 4 = WR
S x 4 = DR
A x 4 = ED
C x 4 = W
W x 4 = CY
Q x 4 = EY
D x 4 = A
Y x 4 = DW
E x 4 = CD

7 x 4 = 28
10 x 4 = 40
5 x 4 = 20
8 x 4 = 32
1 x 4 = 4
4 x 4 = 16
9 x 4 = 36
2 x 4 = 08
6 x 4 = 24
3 x 4 = 12

5 Times Table

F x 5 = K5
T x 5 = KP
L x 5 = 5
5 x 5 = M5
U x 5 = O5
M x 5 = LP
LP x 5 = 5P
K x 5 = MP
O x 5 = L5
H x 5 = OP

9 x 5 = 45
8 x 5 = 40
1 x 5 = 5
5 x 5 = 25
7 x 5 = 35
2 x 5 = 10
10 x 5 = 50
4 x 5 = 20
3 x 5 = 15
6 x 5 = 30

6 Times Table

G x 6 = VG
L x 6 = TG
T x 6 = BR
F x 6 = 6
FR x 6 = 6R
B x 6 = FU
V x 6 = FV
U x 6 = GU
H x 6 = B6
J x 6 = GV

4 x 6 = 24
9 x 6 = 54
5 x 6 = 30
1 x 6 = 6
10 x 6 = 60
3 x 6 = 18
2 x 6 = 12
8 x 6 = 48
6 x 6 = 36
7 x 6 = 42

7 Times Table

7 x 7 = RA
W x 7 = PL
G x 7 = 7
R x 7 = NW
A x 7 = LU
P x 7 = UP
N x 7 = GR
GS x 7 = 7S
L x 7 = RN
U x 7 = NG

7 x 7 = 49
8 x 7 = 56
1 x 7 = 7
4 x 7 = 28
9 x 7 = 63
5 x 7 = 35
2 x 7 = 14
10 x 7 = 70
6 x 7 = 42
3 x 7 = 21

8 Times Table

L x 8 = Z8
P x 8 = TL
V x 8 = DL
Z x 8 = CV
DE x 8 = 8E
D x 8 = 8
C x 8 = VZ
T x 8 = ZE
Y x 8 = LZ
H x 8 = PV

6 x 8 = 48
7 x 8 = 56
2 x 8 = 16
4 x 8 = 32
10 x 8 = 80
1 x 8 = 08
3 x 8 = 24
5 x 8 = 40
8 x 8 = 64
9 x 8 = 72

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