Download Mult - 12 x table stg 5 to E7

The twelve times table.
Stg 5/E6 x/÷
Name: _____________
Twelve times tables? Too hard right? Nope. As with many of the times-tables, the best way to deal with
them is to memorise them so that they become instant recall. On the way though, we sometimes need a
helping hand. Here is a simple strategy that might help you out of a sticky situation:
Take for example 12 x 7 = ?? Often people get stuck on this one – probably because it’s in both in the 7
and 12 times table.
Don’t worry – try this: You know your 10 x tables without even trying. So, just do that first:
10 x 7 = 70 (easy!) … But we’re multiplying by 12! Don’t panic, just double (x2) another 7
(2 x 7 = 14) and stick it on. It looks like this:
70 + 14 = 84. So then, 12 x 7 = 84. Dopey Sneezy, super easy.
This works because 12 = 10 + 2 (gosh really, I had no idea). So, now try some for yourself:
1.
10 x 8 = ____ + (2 x 8) = _____ so 12 x 8 = ____
2.
10 x 6 = ____ + (2 x 6) = _____ so 12 x 6 = ____
3.
10 x 12 = ____ + (2 x 12) = _____ so 12 x 12 = ____
4.
10 x 7 = ____ + (2 x 7) = _____ so 12 x 7 = ____
5.
10 x 4 = ____ + (2 x 4) = _____ so 12 x 4 = ____
6.
10 x 9 = ____ + (2 x 9) = _____ so 12 x 9 = ____
7.
10 x 3 = ____ + (2 x 3) = _____ so 12 x 3 = ____
8.
10 x 11 = ____ + (2 x 11) = ______ so 12 x 11 = ____
9.
10 x 5 = ____ + (2 x 5) = _____ so 12 x 5 = ____
Sarcasm;
The lowest
form of wit.
English is odd. The word
‘twelve’ is strange too. In
most languages they say
a version of ‘ten and two’
E.g. in Te Reo Māori 12 is
‘tekau mā rua’
Now you’ve got the hang of that, practice with these ‘family of facts’:
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
12 x 8 = _____.
12 x 12 = _____.
12 x 7 = _____.
12 x 6 = _____.
12 x 4 = _____.
12 x 9 = _____.
12 x 3 = _____.
12 x 11 = _____.
12 x 5 = _____.
12 x 2 = _____.
12 x 10 = _____.
12 x 8 = _____. _____ ÷ 8 = 12. ____ ÷ 8 = 12
_____ ÷ 12 = 12. (Why only 2 in this family?)
7 x 12 = _____. _____ ÷ 7 = 12. ____ ÷ 12 = 7
6 x 12 = _____. _____ ÷ 6 = 12. ____ ÷ 12 = 6
4 x 12 = _____. _____ ÷ 12 = 4. ____ ÷ 4 = 12
9 x 12 = _____. _____ ÷ 12 = 9. ____ ÷ 9 = 12
3 x 12 = _____. _____ ÷ 12 = 3. ____ ÷ 3 = 12
11 x 12 = _____. _____ ÷ 12 = 11. ____ ÷ 11 = 12
5 x 12 = _____. _____ ÷ 12 = 5. ____ ÷ 5 = 12
2 x 12 = _____. _____ ÷ 12 = 2. ____ ÷ 2 = 12
10 x 12 = _____. _____ ÷ 12 = 10. ____ ÷ 10 = 12
It’s about time: There are 12 hours shown on an analogue clock face, but it goes around twice a day to count 24
hours. There are 12 months in a year, but it wasn’t always so. In the past, cultures have used lunar months, of which
there are roughly 13. The Romans added January and February to their 10-month calendar to make the 12-month
calendar we use today.
Dave Moran 2015
Stg 6 x/÷
The twelve times table.
Name: _____________
OK, we know that we can split 12 into 10 and 2 to make multiplication by 12 easier.
E.g. 10 x 7 =70, 2 x 7 = 14, 70 + 14 = 84, so then 12 x 7 = 84
That’s cool, but can we do the same with bigger numbers? Uh-huh, absolutely we can. In fact there’s two
similar ways we can look at it. First, as we’ve already learned, split the 12 in to 10 and 2. Try some of
these nasty looking ones – you’ll find it’s not too scary:
E.g. 10 x 23 = 230
+ (2 x 23) = 46
so 12 x 23 = 276
1. 10 x 31 = ______ + (2 x 31) = _______ so 12 x 31 = ______
2. 10 x 42 = ______ + (2 x 42) = _______ so 12 x 42 = ______
3. 10 x 53 = ______ + (2 x 53) = _______ so 12 x 53 = ______
In the colour
wheel, there are
12 basic hues: 3
primary, 3
secondary, and 6
tertiary colours.
4. 10 x 44 = ______ + (2 x 44) = _______ so 12 x 44 = ______
5. 10 x 41 = ______ + (2 x 41) = _______ so 12 x 41 = ______
6. 10 x 34 = ______ + (2 x 34) = _______ so 12 x 34 = ______
7. 10 x 32 = ______ + (2 x 32) = _______ so 12 x 32 = ______
Or we can stack numbers up to do the same thing – it takes less room. There are two ways to do this with
12s. Because splitting into 10 + 2 is so easy we can choose to just double the number to start with, or use
our standard algorithm style. No worries either way. As always, the key is to keep your place values and
remember to carry when necessary. Let me give you a couple of examples:
Now fly solo:
x
(2 x 53) =
+ (10 x 53) =
=
c.
x
48
12
h.
x
28
12
b.
g.
E.G. ii.
53
12
106
530
636
a.
1 0
x
x
(2 x 6 = 12, 2 x 70 + 10= 150) =
+ (10 x 76) =
=
76
12
152
760
912
e.
x
27
12
f.
x
94
12
j.
x
74
12
k.
x
62
12
d.
x
31
12
i.
x
78
12
A 12-sided polygon is called a dodecagon. A 12- pentagon faced
polyhedron is a dodecahedron. A group of 12 things can be called
‘duodecad’ or more commonly a ‘dozen’.
73
12
0
x
39
12
x
85
12
The word “twelve” is from the old English
twelf, literally “two left” (over 10).
E.G. i.
Dave Moran 2015
Stg 6/E7 x/÷
The twelve times table.
Name: _____________
Mean, nasty, horrible, frightening and disgusting. Just some of the words used to describe the teacher
that made this worksheet. And yet there is no need to be scared of this maths. Remember, you can
overcome these problems by breaking them down into smaller, easier to chew bits. On these ones, see if
you can multiply by 12 in one gulp – it’s quicker and good for your teeth. (last bit may not be true)
562
x 12
= 6744
1. Multiply 12 x 2 to get 24, the 4 gets put in the ones column under the answer
line, the 2 (actually 20) gets put above the 6
2. Go 12 x 6 = 72. Then add the 2 sitting above to get 74. Put the 4 in the tens
column, but pop the ‘7’ up in the hundreds.
3. Times 12 by 5 to get 60, but also ADD that sneaky 7 you just put there to get 67
(60 + 7 = 67)
4. You’ve done it! Total answer 6744
Now, try some 3 digit fellas:
523
x 12
209
x 12
451
x 12
327
x 12
462
x 12
954
x 12
742
x 12
194
x 12
341
x 12
833
x 12
921
x 12
744
x 12
560
x 12
345
x 12
456
x 12
567
x 12
678
x 12
789
x 12
7819
x
12
47819
x
12
6732
x
12
1432
x
12
56321
x
12
6342
x
12
90658
x
12
8942
x
12
65402
x
12
Because the number 12 has so many factors for being such a low number and is one of
the lowest easily divisible numbers, it is a highly practical and respected number.
7 2 0
99811
x
12
Well, it looks like you’ve had a good go at
those ones already! So here are some challenge questions you can write out and try in your own maths
book. Remember to keep your columns!
a. 385.23 x 12
b. 475.89 x 12
c. 785.34 x 12
d. 674.12 x 12
Dave Moran 2015