Jumping the number line
I am learning to jump through a tidy number on a number
line to solve problems like 17 + …. = 91
Numbers like
10, 20, 30, 40
etc.
SAMPLE PROBLEM
Craig works on the 18th floor of a building and wants to visit
his friend who lives on the 72nd floor of the building. How
many levels must be climb through?
Friend: 72nd floor
Craig: 18th floor
18 + ? = 72
SAMPLE PROBLEM
18 + ? = 72
Step 1: Draw a number line with your starting
point (that’s the level where Craig is working.)
Friend: 72nd floor
Step 2: Write in the end point (that’s the level
where Craig’s friend is working.)
Craig: 18th floor
18
72
SAMPLE PROBLEM
18 + ? = 72
Step 3: Choose a tidy number to jump up
to which takes you just above your target
then write it on your number line.
30 is a tidy number, but it’s
not the closest one
20 is perfect.
+2
18 20
72
SAMPLE PROBLEM
18 + ? = 72
Step 4: Now I think 20 + ? = 72
I know this is 52 so I add this arrow to my
diagram.
+52
+2
18 20
72
SAMPLE PROBLEM
18 + ? = 72
Working out the answer: You jumped up 2 then
up 52 (2 + 52 = 54).
18 + 54 = 72
Friend: 72nd floor
+54
Craig: 18th floor
Now let’s try one together
Sarah works on floor 27 of the office block and wants to
meet her friend who works on the 62nd floor. How many
floors does she need to climb?
27 + ? = 62
Now let’s try one together
27 + ? = 62
Step 1: Draw a number line with your starting
point and end point. Do this now on a piece of
paper.
Now let’s try one together
27 + ? = 62
Step 2: Choose a tidy number to jump up to
which takes you just past your target number
(27).
Do this now.
Now let’s try one together
27 + ? = 62
Step 3: Now find the number you must jump up
to get to the end of your number line (62).
Add this to your drawing now.
Now let’s try one together
15 + ? = 61
Step 4: Now work out how far you had to jump.
(Add your first jump and your second jump
together.)
Do this now.
So…
15 + 35 = 61
Now try these questions on your own.
1) 18 + ….. = 54
6) 17 + ….. = 36
2) 27 + ….. = 62
7) 48 + …. = 94
3) 19 + … = 96
8) 39 + ….. = 63
4) 38 + …. = 81
9) 28 + …. = 73
5) 37 + ….. = 56
10) 58 + …. = 97
Only click again if you have completed all the questions
on the previous slide and you are ready to see the
answers.
1) 36
6) 19
2) 35
7) 46
3) 77
8) 24
4) 43
9) 45
5) 19
10) 39
Need some more practise? Try Pg44 of Teacher Tools Addition and
Subtraction Book Numeracy resources