Addition 1
1. How many additions to 100 can you write in 1 minute? Use 2-digit
numbers. For example, 25 + 75 = 100 or 21 + 79 = 100
100
100
All possible answers (order can be reversed!):10 + 90; 11 + 89; 12 + 88; 13 + 87; 14 + 86; 15 + 85; 16 + 84; 17 + 83;
18 + 82; 19 + 81; 20 + 80; 21 + 79; 22 + 78; 23 + 77; 24 + 76; 25 + 75;
26 + 74; 27 + 73; 28 + 72; 29 + 71; 30 + 70; 31 + 69; 32 + 68; 33 + 67;
34 + 66; 35 + 65; 36 + 64; 37 + 63; 38 + 62; 39 + 61; 40 + 60; 41 + 59;
42 + 58; 43 + 57; 44 + 56; 45 + 55; 46 + 54; 47 + 53; 48 + 52; 49 + 51;
50 + 50.
2. Roll a dice four times (or choose from numbers 1-6 on pieces of paper) and
write the digits in this form □□00 + □□00. Find the total. What is the biggest
answer you could get with these digits? And the smallest? Have another go.
I rolled:
6 2
3
6200 + 3500
= 9700
Largest answer
possible
6300 + 5200 =
11,500
Smallest answer
possible
2500 + 3600 =
6100
3600 + 3100
= 6700
2500 + 4100
= 6600
6300 + 3100
= 9400
5200 + 4100
= 9300
1300 + 3600
= 4900
1400 + 2500
= 3900
Addition
5
3 6 3 1
2 5 1 4
3. Repeat using this form: □□,000 + □□,000.
Largest answer
I rolled:
Addition
possible
43,000 + 25,000 = 43,000 + 52,000
4 2 3 5
= 95,000
68,000
21,000 + 36,000 =
57,000
54,000 + 24,000 =
4
78,000
2 1 3 6
5 4 2
HSNP © Hamilton 2013
62,000 + 31,000
= 93,000
54,000 + 42,000
= 96,000
Simmering Term 1
Smallest answer
possible
25,000 +
34,000 = 59,000
13,000 + 26,000
= 39,000
24,000 + 45,000
= 69,000
Page 3
Addition 1
4. Use all the digits from 2 to 9 to make pairs of four-digit numbers. For
example, 2345 + 6789 = 913
Find a pair with the biggest possible total, the smallest possible total and a
total as close to 8000 as you can.
9753 + 8642 = 18,395 Biggest total
2468 + 3579 = 6047 Smallest total
5649 + 2378 = 8027 Closest to 8000
If you have internet access, try this
Play Speedy Grid Challenge at bit.ly/13pRdr7. Try
to answer 10 questions in three minutes. You will
be given a number.
Find 2 numbers in the grid that make this total.
How many questions did you answer in 3 turns?
Score turn 1:
Score turn 2:
Score turn 3:
________
________
________
This is a computer game.
just right
too hard
3
How did you find these problems?
1
2
Page 4