Question

7. Mention a past year that has no change when put upside down.

Answer 1

Answer:these are called

strobogrammatic number is a number whose numeral is rotationally symmetric, so that it appears the same when rotated 180 degrees

Step-by-step explanation:the last ones we had were in 1881 and 1961 the next will be in 6009

Answer 2

Strobogrammatic numbers:

The strobogrammatic numbers are those numbers which if rotated by 180 degrees, result the same as before.

Examples: 0, 1, 8, ..., 69, 96, 101, ..., etc.

Strobogrammatic primes:

The strobogrammatic numbers which are also prime numbers, are called strobogrammatic primes.

Examples: 11, 101, 181, ..., etc.

Answer:

The past years which have no change when written upside down or rotated 180 degrees are

1691

1881

1961

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