Page 62 - 01-Yr5_Front cover-ccp.indd

II

OJ 1, 3 and 6 are the first three triangular numbers

since they can be arranged in a triangular pattern.
Continue this pattern until you have drawn the next three .
•
• • •
• • • • • •

1 1 + 2 = 3 1 +2+3=6

[I] Design arrow diagrams like this one 3rd triangular number

for the 7th and 8th triangular numbers.
/\

@] Without drawing diagrams,

show how you can work out 1+2+3 6
the 9th and 10th triangular numbers.

[i:J a Copy and complete this difference pattern
for the first ten triangular numbers.

1 3 6 10
~/~/~/~/~/~/\/~/~/

2 3
'\/
1
b Write what you think the blue numbers stand for.
c Write what you think the red numbers stand for.

CHALLENGE
•
a••
• Explain why these do not
show triangular numbers. • •
• •
•••••

• • STEPS 5:14