2-min Fluency Warm-up — Skip count. Fill in the missing numbers.
Count by 8s, then by 9s.
Count by 8:
Count by 9:
The 9s Secret! Look at the 9s: 9, 18, 27, 36, 45... The two digits of every answer add up to 9! (1+8=9, 2+7=9, 3+6=9). And the tens digit is always ONE LESS than the number you multiplied. Try it:
9 × 4
Tens digit (one less than 4):
Ones digit (digits add to 9):
9 × 4 =
9 × 6
Tens digit (one less than 6):
Ones digit (digits add to 9):
9 × 6 =
9 × 8
Tens digit (one less than 8):
Ones digit (digits add to 9):
9 × 8 =
9 × 7
Tens digit (one less than 7):
Ones digit (digits add to 9):
9 × 7 =
Strategy: 8s are triple-doubles! To find 8 × 3: double 3 (=6), double again (=12), double once more (=24). Try it:
8 × 4
Double 4: → Double: → Double:
8 × 4 =
8 × 2
Double 2: → Double: → Double:
8 × 2 =
8 × 5
Double 5: → Double: → Double:
8 × 5 =
8 × 3
Double 3: → Double: → Double:
8 × 3 =
Write the multiplication sentence and solve. Use any strategy!
An octopus has 8 arms. How many arms do 3 octopuses have?
Multiplication sentence:
arms
A baseball team has 9 players. How many players are on 4 teams?
Multiplication sentence:
players
Number Talk — Explain WITHOUT multiplying.
Tom says 9 × 6 = 56.
Use the 9s secret to check — could 56 be right?
My thinking:
Which is easier for YOU: 8 × 2 or 2 × 8? Why?
My thinking: