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Gurujada

Multiply near 100

Multiply numbers like 98 × 97 in your head in four moves — and see how Gurujada notices a mistake and helps you fix it.

Self-paced · from 30 Sep 2026 Anyone new to Gurujada: learners and teachers Open to join

K With Krishnamohan

A 25-minute tour of Gurujada built around one mental-maths method. Watch a short video, read why the method works, practise with instant reasons for each mistake, check your understanding with Vidya, and — if you teach — see how a teacher watches a learner's journey and corrects it.

No sign-up is needed for the preview lessons and the first practice sheet. Join to keep your answers, unlock the second Section and try an understanding check.

You'll be able to

  • Read a near-100 product as two blocks: left and right.

  • Find each number's deficit from 100.

  • Explain why the right block of a base-100 answer always has two digits.

  • State the four moves in order.

  • Use (100-a)(100-b) = 100(100-a-b) + ab to explain the left and right blocks.

  • Multiply two numbers between 90 and 99 mentally.

  • Recognise a dropped zero in the right block.

  • Write every base-100 right block with exactly two digits.

  • Carry the hundreds of an overflowing right block into the left block.

  • Use surpluses for numbers above 100.

  • Carry an overflowing right block.

  • Multiply two numbers just above 100.

  • Find and explain an error in written working.

What's inside

3 Sections 4 documents 2 practice sheets 2 videos 5 m of video and audio

Try it, free

98 × 97 in four moves Preview video · 2 min Why the four moves work Preview document · 3 min Try the four moves Preview practice · 7 min Watch a teacher correct a journey Preview video · 3 min What your teacher sees Preview document · 3 min

Outline

Four moves below 100

Document

Keep two digits on the right

2 min

Carry, and numbers above 100

After the previous Section

Document

When the right block overflows

3 min

Practice

Stretch the method

8 min

For teachers: watch and correct

How you'll learn here

  • Vidya, this Workbook's assistant, asks you questions when you're stuck. It never gives the answer.
  • Sections open one after another as you finish them.
  • Your teachers see your work and reply.

Your teachers

K

Krishnamohan