https://wiki.apterous.org/index.php?action=history&feed=atom&title=Four-large_rules 2026-05-23T21:50:45Z Revision history for this page on the wiki MediaWiki 1.31.5 https://wiki.apterous.org/index.php?title=Four-large_rules&diff=171288&oldid=prev 2024-09-16T02:35:13Z

<p>New page</p> <p><b>New page</b></p><div>This page details the many different rules to help play four-large [[numbers round]]s on ''[[Countdown]]''.<br /> <br /> ==Simpler rules==<br /> *50 ÷ 25 = 2 or 100 ÷ 50 = 2<br /> *75 ÷ 25 = 3<br /> *100 ÷ 25 = 4<br /> *(75 + 50) ÷ 25 = 5<br /> *(100 + 50) ÷ 25 = 6<br /> *(100 + 75) ÷ 25 = 7<br /> *(100 + 75 + 50) ÷ 25 = 9<br /> ----<br /> *100 + 75 + 50 + 25 = 250<br /> *50 ÷ 25 × 100 + 75 = 275<br /> *75 ÷ 25 × 100 + 50 = 350 or (100 + 75) × 50 ÷ 25 = 350<br /> *(100 + 50) × 75 ÷ 25 = 450<br /> *(75 − 50) × 25 = 625 or (100 − 75) × 25 = 625<br /> **(75 − 50) × 25 − 100 = 525<br /> **(100 − 75) × 25 − 50 = 575<br /> **(100 − 75) × 25 + 50 = 675<br /> **(75 − 50) × 25 + 100 = 725<br /> <br /> ==Complex rules==<br /> *(75 × 50 ± 100) ÷ 25 = 146/154<br /> *(100 × 50 ± 75) ÷ 25 = 197/203<br /> *(100 × 75 ± 50) ÷ 25 = 298/302<br /> <br /> The small numbers can also be added or subtracted before the multiplication to extend this further:<br /> <br /> ====Example 1====<br /> 25 50 75 100 3 3 → 160<br /> <br /> {{Spoiler|((75 + 3) × 50 + 100) ÷ 25|Answer|align=center|float=left|width=20%}}<br /> &lt;div style=clear:both&gt;&lt;/div&gt;<br /> <br /> ===937.5 rule===<br /> This rule is based around the calculation:<br /> <br /> *25 × 50 × 75 ÷ 100 = 937.5<br /> <br /> As decimals are not allowed in ''[[Countdown]]'', small numbers are required to make an integer. This is done in the following ways:<br /> <br /> *(25 × 75 ± [odd number]) ÷ (100 ÷ 50)<br /> *(50 × 75 ± [4n + 2]) ÷ (100 ÷ 25) '''(n ≥ 0)'''<br /> *(25 × 50 ± [4n + 2]) × 75 ÷ 100 '''(n ≥ 0. It is required to do the × 75 first in order to keep it an integer)'''<br /> <br /> ====Example 1====<br /> 25 50 75 100 3 3 → 939<br /> <br /> {{Spoiler|(25 × 75 + 3) ÷ (100 ÷ 50)|Answer|align=center|float=left|width=20%}}<br /> &lt;div style=clear:both&gt;&lt;/div&gt; <br /> <br /> ====Example 2====<br /> 25 50 75 100 2 2 → 937<br /> <br /> {{Spoiler|(50 × 75 − 2) ÷ (100 ÷ 25)|Answer|align=center|float=left|width=20%}}<br /> &lt;div style=clear:both&gt;&lt;/div&gt;<br /> <br /> ====Example 3====<br /> 25 50 75 100 6 6 → 942<br /> <br /> {{Spoiler|(25 × 50 + 6) × 75 ÷ 100|Answer|align=center|float=left|width=20%}}<br /> &lt;div style=clear:both&gt;&lt;/div&gt;<br /> <br /> ==Very complex rules==<br /> *25 × 100 ÷ (75 + 50) = 20<br /> *50 × 75 ÷ (100 + 25) = 30<br /> *(100 × 25 + 50) ÷ 75 = 34<br /> *(100 × 50 + 25) ÷ 75 = 67<br /> <br /> ==External Links==<br /> *[https://web.archive.org/web/20160418023337/http://www.jerryh.pwp.blueyonder.co.uk/countdown/fourlargenumbers.htm Archive version of four-large number tips] by [[Jerry Humphreys]]<br /> <br /> [[Category:Study aids]]<br /> [[Category:Techniques]]</div>

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