Mirror Maths

A Maths Starter of The Day

The bottom half of some symmetrical calculations are shown above. Can you work out the answers?

Can you make up some other calculations where the calculation and the answer both have horizontal lines of symmetry?

[Teacher: pull down the mirror at the top of the screen to show the top halves of the calculations]

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Topics: Starter | Arithmetic | Puzzles | Symmetry | Transformations

  • Aimee Hamilton, Harrytown Catholic High School
  • Thursday, March 08, 2007
  • "80+101=181"
  • Abigail Latham, Swinton
  • Saturday, March 10, 2007
  • "Hello.
    Im Abigail Latham From St. Charles Rc Primary School Swinton Manchester
    And I Found That 300+100+300+300=1000
    30+30+30+10=100
    10x10=100"
  • Abz :D, St Charles Rc Primary
  • Wednesday, March 14, 2007
  • "100+300+300+300=800
    800x10=8000
    0x10=0
    300.08x10=3000.8
    =]:D"
  • Alice K, St Matts
  • Wednesday, March 10, 2010
  • "100 + 88 +111 +1 = 300."
  • Primary 7, Bargeddie Primary School
  • Wednesday, March 10, 2010
  • "We enjoyed this starter, especially since one of our groups are studying symmetry...
    Here are some of our examples:
    333 - 333 + 1 = 1
    33 x 3 + 1 = 100
    11 x 3 = 33
    111 - 111 + 8 = 8
    Callum in our class also noticed that multiplying any combination of multiples of 10 would give a symmetrical answer:
    e.g. 1000 x 1000, 1 000 000 000 x 1000, 10 x 100 000 000 000 etc."
  •  

  • Mr. T, Gartree High School
  • Wednesday, March 10, 2010
  • "Good for younger groups like year 7s since the sums are pretty straight forward but they liked trying to work out how to reflect the digits."
  • Tomiloba Awosika, Bishop Challoner School
  • Thursday, March 10, 2011
  • "Tomiloba from Bishop Challoner School 8B3 has come up with an example - 300 + 300 + 300 - 100 = 800."
  • Prendergast, Prendergast 9.1 Maths
  • Thursday, March 10, 2011
  • "11 + 11 + 11 = 33
    11 + 11 + 38 + 10 + 10 = 80
    8 x 1 = 8
    11 x 3 = 33
    11 x 8 = 88
    13 + 18 = 31
    3 x 1 = 3
    1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 = 8
    1 + 1 + 1 = 3
    symmtrical number x 0 = 0."

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This starter has scored a mean of 3.6 out of 5 based on 75 votes.


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Answers
l l + 38 = 49

88 x 33 = 2904

838 - 383 = 455

l 8 l x l l = 1991

3 l + 3 l + 3 l = 93

l 0 x l 0 l + l l l = 1121

l 8 l x l 3 l - 80 = 23631

l 380 + 38 - 83 = 1335

Here's an example where the calculation and the answer both have horizontal lines of symmetry?

l00 + l l l + l l + l l l = 333

If you can find any other interesting examples please let us know here.

 

Your next challenges are to make:
  • An equation with a horizontal and vertical line of symmetry

  • A mathematical ambigram

Ambigrams were made famous
in Dan Brown's novel "Angels and
Demons"