Behold the challenge! The tally escalates to ‘twenty, twenty-one’
Count von Count shall be brimming with fervor. For the premiere instance since 1920, the impending annum, 2021, unfolds as a pair of successive, ascending numerals. Revel in this ‘enumerating date’ whilst it endures, esteemed individuals! It shan’t recur for another century and a score of years.
The conundrums presented today unveil further numerical patterns regarding 2021.
- Countdown riddle
The initial query is an annual tradition. Fill in the lacunae in the ensuing equation to render it arithmetically coherent:
10 9 8 7 6 5 4 3 2 1 = 2021
You possess the liberty to employ any of the fundamental mathematical operations, +, –, x, ÷, and as numerous brackets as you deem fit. A solution might resemble something akin to (10 – 9 + 8) x (7 – 6 – 5)/(4 + 3 + 2 + 1) = 2021, albeit not identical to this example as the equation proves erroneous.
There exist myriad correct solutions – endeavor to discern the most refined one.
- Inder’s enigmas
Inder J Taneja, a retired mathematics luminary from Brazil, derives pleasure in fashioning descriptions of the novel date using amalgamations of the identical numeral. For instance, here’s his rendition with 1.
(1+1)11 −(1+1+1)(1+1+1) = 2021
Can you discover amalgamations of 2’s, 3’s, 4’s 5’s, 6’s, 7s, 8’s and 9’s that also amount to 2021? You are only permitted to utilize a maximum of ten digits per equation. (Attempt at least one.) However, you can amalgamate, i.e., position two or more digits together in the same number, as illustrated above with 11.
- Marek’s mindbender
The Polish conundrum craftsman Marek Penszko submitted the grid puzzle underneath, which you can procure here.
You must imbue each of the nine vacant cells so that all the equations hold true. Each cell mandates a solitary digit. Since 0, 1 and 2 are already discernible, the sole digits that can inhabit the vacant cells are those from 3 to 9, some of which repeat. The computations must adhere strictly from left to right, or from top to bottom (i.e., disregard operator precedence). [note: the ‘:’ denotes division.]
I shall return at 5pm UK time with a compilation of my preferred 2021 equations and solutions to the riddles. Kindly populate the comments beneath the line with as many numerical peculiarities regarding 2021 as you are able!