Triangle Numbers

What is the pattern?

• Multiply by 2
• Add the next number
• Subtract the next number
• Divide by 3

What is the 6th triangle number?

• 15
• 120
• 21
• 6

How many triangle numbers are there?

• 77
• 50
• 121
• Infinity

What are the first 5 triangle numbers?

• 1, 3, 6, 10, 15 
• 1, 4, 7, 9, 10
• 0, 2, 5, 6,12
• 2, 3, 5, 7, 9

What is the 10th triangle number?

• 66
• 55
• 45
• 78

What is the 4th triangle number?

• 15
• 3
• 10
• 21