Fourth Grade · Math · week 10

Multiplying by 10s and 100s

Multiply whole numbers by 10, 100, 1,000, and multiples of ten using place-value patterns.

Multiplying by 10 shifts every digit one place value bigger; by 100 it shifts two places; by 1,000 it shifts three places. That is why 6 x 10 = 60 and 6 x 100 = 600: the digits are not randomly "gaining zeros," they are moving into bigger place values.

For a number like 30 or 400, split it into a basic fact times a power of ten. To find 6 x 400, think 6 x 4 = 24, then attach two zeros for the hundred: 2,400.

📋 For the teacher
Teach it (10–15 min):
  • Connect the shortcut to base-ten blocks: a tens stick becomes a hundreds flat when multiplied by 10, because each place is worth ten times more.
  • Have them solve the small basic fact first (like 6 x 4), then attach the zeros from the powers of ten afterward.
  • Watch closely when both factors have zeros (like 40 x 60); every zero from both numbers has to show up in the answer.
  • Remind them this "shift" idea only makes multiplying by 10, 100, and 1,000 fast; it does not work as a shortcut for other numbers.
Talk about it:
  • Why does multiplying by 10 shift the digits instead of just randomly adding a zero?
  • How do you break 40 x 60 into an easier basic fact?
  • How many zeros will 200 x 300 have, and why?

Mastery looks like: They multiply whole numbers by 10, 100, 1,000, and multiples of ten instantly using place-value reasoning.

Common stumbles: Attaching the wrong number of zeros when both factors already have zeros; treating "add a zero" as a shortcut for facts that are not powers of ten.

See it visually

Interactive, spoken-aloud tools that show this idea in motion.

MultiplicationEqual groups and arrays make products finally click.try →
Homework for this lessonType it, write it with a stylus, or print it for pencil & paper.open →
Records attendance + 15 min of Math for this learner.
← Back to todayAll coursesYear planner