Rekenen met datum en tijd

Aangezien \(t = 0\) overeenkomt met 1 januari, komt \(t = 244\) overeen met \(245 \text{ } \text{januari} \text{.}\)

\(245 \text{ } \text{januari}\)
\(\text{ } = 245 - 31 \text{ (januari)} = 214 \text{ } \text{februari}\)
\(\text{ } = 214 - 28 \text{ (februari)} = 186 \text{ } \text{maart}\)
\(\text{ } = 186 - 31 \text{ (maart)} = 155 \text{ } \text{april}\)
\(\text{ } = 155 - 30 \text{ (april)} = 125 \text{ } \text{mei}\)
\(\text{ } = 125 - 31 \text{ (mei)} = 94 \text{ } \text{juni}\)
\(\text{ } = 94 - 30 \text{ (juni)} = 64 \text{ } \text{juli}\)
\(\text{ } = 64 - 31 \text{ (juli)} = 33 \text{ } \text{augustus}\)
\(\text{ } = 33 - 31 \text{ (augustus)} = 2 \text{ } \text{september}\)

Aangezien \(t = 0\) overeenkomt met 29 september 2018, komt \(t = 110\) overeen met \(29 + 110 = 139 \text{ } \text{september} \text{.}\)

\(139 \text{ } \text{september}\)
\(\text{ } = 139 - 30 \text{ (september)} = 109 \text{ } \text{oktober}\)
\(\text{ } = 109 - 31 \text{ (oktober)} = 78 \text{ } \text{november}\)
\(\text{ } = 78 - 30 \text{ (november)} = 48 \text{ } \text{december}\)
\(\text{ } = 48 - 31 \text{ (december)} = 17 \text{ } \text{januari}\)
Dus bij \(t = 110\) hoort 17 januari 2019.

13 juni 2022 is \(t = 0\)
30 juni 2022 is \(t = 30 - 13 = 17\)
31 juli 2022 is \(t = 17 + 31 = 48\)
31 augustus 2022 is \(t = 48 + 31 = 79\)
30 september 2022 is \(t = 79 + 30 = 109\)
6 oktober 2022 is \(t = 109 + 6 = 115\)

\(t = 41\) komt dan overeen met \(\text{1990} + 41 = \text{2031} \text{.}\)

\(\text{1982}\) komt dan overeen met \(t = \text{1982} - \text{1975} = 7 \text{.}\)

De maand augustus heeft \(31\) dagen.

De \(5\)e maand van het kalenderjaar is \(\text{mei} \text{.}\)

Op \(t = 7{,}995\) is het \(7 \text{ } \text{uur}\) en \(0{,}995 ⋅ 60 = 59{,}7 \text{ } \text{minuten}\) later dan \(\text{3:00} \text{ } \text{uur} \text{.}\)
Het is dan dus \(\text{10:59} \text{ } \text{uur} \text{.}\)

Om \(\text{20:53} \text{ } \text{uur}\) is het \(10 \text{ } \text{uur}\) en \(53 \text{ } \text{minuten}\) later dan \(\text{10:00} \text{ } \text{uur} \text{.}\)
Dat is dus bij \(t = 10 + {53 \over 60} = 10{,}88333... \text{.}\)

\(18{,}1 \text{ } \text{uren} = 18{,}1 ⋅ 3\,600 \text{ } \text{seconden} = 65\,160 \text{ } \text{seconden}\)

\(174 \text{ } \text{seconden} = 174 : 60 \text{ } \text{minuten} = 2{,}9 \text{ } \text{minuten}\)

\(0{,}92 \text{ } \text{jaar} = 0{,}92 ⋅ 12 = 11{,}04 \text{ } \text{maanden} \text{,}\) dus \(8{,}92 \text{ } \text{jaar} = 8 \text{ } \text{jaar}\) en \(11 \text{ } \text{maanden} \text{.}\)

\(2 \text{ } \text{minuten}\) en \(55 \text{ } \text{seconden} = 2 + {55 \over 60} = 2{,}916... \text{ } \text{minuten} \text{.}\)

\(9 \text{ } \text{dagen} = 9 ⋅ 24 ⋅ 3\,600 = 777\,600 \text{ } \text{seconden}\)
\(23 \text{ } \text{uren} = 23 ⋅ 3\,600 = 82\,800 \text{ } \text{seconden}\)
\(19 \text{ } \text{minuten} = 19 ⋅ 60 = 1\,140 \text{ } \text{seconden}\)
Dus \(777\,600 + 82\,800 + 1\,140 + 7 = 861\,547 \text{ } \text{seconden}\)

\(307\,763 \text{ } \text{seconden} = {307\,763 \over 24 ⋅ 60 ⋅ 60} = 3{,}562... \text{ } \text{dagen}\)
\(0{,}562... \text{ } \text{dagen} = 0{,}562... ⋅ 24 = 13{,}489... \text{ } \text{uren}\)
\(0{,}489... \text{ } \text{uren} = 0{,}489... ⋅ 60 = 29{,}383... \text{ } \text{minuten}\)
\(0{,}383... \text{ } \text{minuten} = 0{,}383... ⋅ 60 = 23 \text{ } \text{seconden}\)
Dus \(3 \text{ } \text{dagen} \text{,}\) \(13 \text{ } \text{uren} \text{,}\) \(29 \text{ } \text{minuten}\) en \(23 \text{ } \text{seconden} \text{.}\)

\(1 \text{ } \text{jaar} = 52 \text{ } \text{weken}\)