D nim ngoli (o).
7, dugc sd du ltr n).
Bu6'c 3. BIt cldu tri di6m mI cria th6ng trOn
ng6n tay ctra minh (dugc x6c dinh theo trmg nlm)
b4n h1y ddm tri I ddn ,4 rheo chidu kim ddig hd.
Didm kdt thric se (mg vdi rhri trong tudn.
Thi dU 1. Dd x6c dinh nghy 20l5l2OO1roi vdo
thrl mdy ta tinh nhu sau :
Budrc 1. M[ cria th6ng 5lI B (ung v6itt B(m)
Budc 2. Ta c6 m = 20, m= 6 (rnod 7), n = 6 :
TO LICH
TREN MOT NGON TAY
XUANTRUNG
(Vi2n Cdng nghQ rh1ng tin)
ngly ttr th6ng 3 trd di phii rinh th€m mQr don vi. Nhu vfly kdt quA tim dugc rheo cic:h tinh n6i rren
se duqc cQng thOm 1 ndu tinh tri th6ng 3 cl0n
thing 12. Circkdt qut cira thSng giOng vX hai v6n
giil nhu cr1.
- Vdi nlm 2000 ngly 111/2000 roi vlo rhri b[y,
d6 l) didm A trOn ng6n tay nhu hinh ve b0n.
Thf dq 2. Ngdy 19/5/2000 roivdo th* mdy ?
Mtr cria th6ng 5 lI B. Tri didm B coi lI 1 ra
rldm ddn n = 5 vi 19 : 5 (mod 7), s0 tim dugc
didm kdt thfc fmg vdi 5 lh E. Do n6rn 2000 ltr
nhudn nOn kdt qul se lh thri s6u.
Thi du 3. Ngdy 3/2/2000 roi vdo thft mdy ?
MX cria thdtg 2 ia D (tmg vdi tri Dfrng. Tn
didm D coi ltr 1 ra ddm ddn 3 didm kdr rhri; iA E
ung vdi thri Ndm.
Gidi thich : C6ch tinh mtr thing 0 b[ng rrOn dUa vdo nhfln xdt sau : vdi c6c ntrm khOng ph6i lh nhufln thi c6c thdng sau ddy se c6 nghy rldu th6ng
rcri vtro ctng mQt tht vtr qo th}nh cfc nh6m lQch
nhau 1 ngtry tinh theo mOdun 7.
MAA MXB MAC MAD vb 11. MAD nh6m 0 (mod 7) g6m 2 rh6ng 1 vI 10. nh6m I (mod 7) gdm th6ng 5. nh6m 2 (mod 7) gdm th6ng 8. : nh6m 3 (mod 7) gdrn c6c thdng 2, 3 nh6m 4 (mod 7) gdm thdng 6 Ma E : nh6m 5 (mod 7) gdm 2 rh6ng 9 vd 12. Ma G : nh6m 6 (mod 7) gdm 2 thtrrg 4 vd,7.
Cdn vdi c6c nf,m nhufln, nhudt n6i, do thdng2 c6 29 ngty nOn kd tri rh6ng 3 ddn rh6ng tZ ndm nhufln ta ph6i cQng kdt qufl thOm 1 don vi.
Cudi cing, luu f ban rlgc ring nlm nhufln duqc
nhfln bidt theo c6c dfu hiQu sau :
1. Ndu tfln cung ld 2 chri sd 0 ttri sd n[m d6
ph6i chia hdt cho 400
2. Ndu khOng tfln cing tI 2 chrl sd 0 thi phli
chia hdt cho 4.
Chtng h4n cdc nim1964 vI 2000 se ld nhufln
cdn nf,m 1990 thi khOng (Di nhiOn chfng ra chi
x6c dinh cho nhimg ndm c6 t6i da 4 chri sd).
D SAu
E Biv
G (.N
Brdc 3. T3i B tinh lI
I ddm 6 lin theo chi6u
kim ddng hd. Didm k6t
thric nng vdi 6Itr G roi